Symposium Organizers
Ji Su NASA Langley Research Center
Li-Peng (Leo) Wang TricornTech Corporation
Yasubumi Furuya Hirosaki University
Susan Trolier-McKinstry The Pennsylvania State University
Jinsong Leng Harbin Institute of Technology
V1: Magnetostrictives
Session Chairs
Monday PM, December 01, 2008
Commonwealth (Sheraton)
9:30 AM - **V1.1
Magnetomechanical Behavior of Iron-Gallium Alloys.
Jayasimha Atulasimha 1 , Alison Flatau 2
1 Mechanical Engineering, Virginia Commonwealth Univ., Richmond, Virginia, United States, 2 Aerospace Engineering, University of Maryland, , College Park, Maryland, United States
Show Abstract10:00 AM - V1.2
Magnetostrictive Fe-Ga Wires with <100> Fiber Texture.
Shannon Farrell 1 , Patti Quigley 1 , Kyle Avery 1 , David Bligh 1 , Allison Nolting 1 , Timothy Hatchard 2 3 , Stephanie Flynn 2 , Richard Dunlap 2 3
1 Dockyard Laboratory (Atlantic), Defence R&D Canada, Dartmouth, Nova Scotia, Canada, 2 Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada, 3 Institute for Research in Materials, Dalhousie University, Halifax, Nova Scotia, Canada
Show AbstractFe-based alloys that combine toughness, formability, and mechanical strength with large magnetostriction are becoming increasingly more popular for use as magnetostrictives. In particular, Fe-Ga alloys, that exhibit approximately 20 % of the strain of traditional rare earth element-based giant magnetostrictive alloys (ex., Terfenol-D), are more robust, less expensive and more versatile (may be employed in tension). Fe-Ga magnetostrictives hold promise for energy harvesting applications that supplement battery power to alleviate strain put on current power storage media.Recently, low-cost processing approaches that produce textured thin bodies have engendered interest as a cost-effective approach for fabrication of Fe-Ga alloys. In particular, wire-forming methods that strictly control the solidification direction could lead to some measure of crystallographic texture control that is required for the development of large magnetostriction. The Taylor wire method for processing Fe-Ga alloys is similar to other non-equilibrium techniques (melt spinning, mechanical alloying, etc.) and is both interesting and promising for preparation of magnetostrictive wire. In this paper, the Taylor wire method will be discussed relative to other non-equilibrium techniques for production of textured Fe-Ga magnetostrictive alloys. The influence of parent material (form and composition), experimental drawing techniques and annealing/quench approaches to wire development will be discussed in terms of the resultant microstructure, crystallographic texture and magnetostriction. Results show that the Taylor wire method is an effective and versatile means to draw 1-3 mm diameter textured Fe-Ga wire. Modification of the parent material, temperature and drawing speed led to a variety of wire morphologies while quench conditions had a profound effect on texture development. In the absence of quenching, the 2-3 mm diameter wires showed no indication of a preferred fiber texture. Experimentation with quench conditions on texture development resulted with the production of a strong <100> fiber texture. Preliminary magnetostriction measurements, in the absence of prestress, indicated a maximum magnetostriction of ~160 ppm in a saturation field less than 0.2 Tesla. Magnetostriction values were similar to that expected for oriented Fe-Ga bulk materials with similar composition (up to 170 ppm strain along <100>) and are considered a significant strain for bulk polycrystalline alloys without a pre-stress or a stress-annealing treatment.
10:15 AM - V1.3
Rapid-solidified Magnetostrictive Polycrystalline Strong-Textured Galfenol (Fe-Ga) Alloy and its Applications for Micro Gas-valve.
Chihiro Saito 1 , Teiko Okazaki 2 , Yasubumi Furuya 3
1 NJC Research Center , Namiki Precision Jewel Co.,Lt, Tokyo Japan, 2 Physical Science , Hirosaki University , Hirosaki Japan, 3 Intelligent Machines and System Engineering, Hirosaki University, Hirosaki Japan
Show AbstractPolycrystalline strong-textured Galfenol (Fe-Ga) alloy ribbon was fabricated by rapid-solidification melt-spinning method. Based on the characterization and discussion of the enhanced magnetostrion mechanism in the ribbon samples, the proto–type micro gas-valve was developed by using bimorph type Galfenol actuator. In recent, A.Clark found that the FeGa (Ga=17-19at%) single crystal showed considerably large magnetostriction of 400 ppm in low magnetic field. however, their fabrication process is not so easy and very expensive. As we know, the advantage of melt-spinning method is extension of solid solubility, grain refinement, reduction or elimination of micro-segregation, and formation of non-equilibrium metastable phase during one process. If the disordered A2 phase at high-temperature region can be frozen to room temperature without precipitating the ordered phases such as fcc ordered L12 as well as bcc ordered D03 phases, more large magnetostriction can be expected even in polycrystalline structure.The former part of this paper, the experimental results of the changes of magnetostriction in the rapid-solidified Fe-Ga system ribbons after heat treatment etc. are overviewed including their special unique microstructures. In fact, the melt-spun, rapid solidified Galfenol (Fe-Ga, (Ga=17-19at%) ribbon sample showed clear angular dependency on magnetostriction and large magnetostriction (=180-200ppm). This large magnetostriction is caused by non-precipitating of the ordered phases, the release of considerable large internal stresses in as-spun ribbon as well as the remained [100] oriented strong textures. These bring the materials improvement in strength toughness, hardness, wear resistance, heat resistance, and corrosion resistance and these seem worthy for engineering application for a actuator/sensor devices. Therefore, in the latter part of this paper, we will introduce the magnetically controllable micro gas-valve which is composed by the bimorph-type FeGa/Ni or FePd /Ni thin plates with the opposite value (FeGa(+), FePd(+), Ni(-)) of magnetostriction coefficient. Large displacement of opposite type could be obtained and their hysteresis curve changed depending on the volume fraction of the composite structure, The dynamic properties of the developed prototype magnetic micro-gas valve will be shown in more detail.
10:30 AM - V1.4
Development of Actuators and Motors Based on Giant Magnetostrictive Materials by a Modular Innovative Approach.
Nanjia Zhou 1
1 , Pittsburg State University, Pittsburg, Kansas, United States
Show Abstract10:45 AM - V1.5
Development of Fe-Ga-Al(Galfenol) System Alloys with Large Magnetostriction and High Strength by Precipitation Hardening of the Dispersed Carbides.
Toshiya Takahashi 1 , Teiko Okazaki 1 , Yasubumi Furuya 1
1 Science and Technology, Hirosaki university, Hirosaki Japan
Show Abstract While magnetostriction materials is observed in all ferromagnetic materials, new materials that exhibit large Joule magnetostriction, at low magnetic fields, are of interest for actual engineering use as acoustic sensors and generators, motors, actuator, damping devices, torque sensors, poisoning devices, transducer etc.. The earliest crystalline magnetostriction alloys used in transducer were Nickel based alloy (Ni-Co system alloys etc λmax=30ppm), and then, large magnetostriction values was obtained in RFe2 intermetallic compounds C15 structure(R=rare-earth elements) such as Terfenol-D alloy with a composition (Dy0.7Tb0.3) Fe2. These alloys show magnetostriction as large as 1000ppm. However, Dy and Tb are high costs, and C15 structure is brittleness, and high fields required for magnetic saturation. In recent work, Fe-Ga and Fe-Ga-Al alloy (Galfenol) produced by Clark et al. Fe-Ga system alloy have A2 structure with (1) high mechanical strength compared to Terfenol, (2) good ductility, (3) large magnetostriction value, (4) low saturation fields, (5) low material prices. However, a strength property is required for industrial application since various applications for actuator/sensor devices are required recently under severe environment, and component mass saving in the machinery etc. This study’s purpose is development of Fe-Ga-Al (Galfenol) system alloy with large magnetostriction and high strength by precipitation hardening effect of the dispersed carbides for application under severe environment and down-sizing. Three kinds of composition bulk samples with additional elements of Carbon, Zirconium, Niobium and Molybdenum to Fe-Ga-Al alloy, (Fe-Ga0.15-Al0.05) 99.0-X0.5-C0.5 (X=Zr, Nb, Mo) [at.%], were prepared. Those bulk samples were given heat treatment after the arc melting. Then, metallurgical characterizations, the magnetic characteristic, magnetostriction characteristic under a free-compressive stress condition and strength property were studied. As a result, (Fe-Ga0.15-Al0.05)99.0-Zr0.5-C0.5 [at.%] arc melted and annealed sample showed a maximum magnetostriction of λmax=90ppm and tensile stress σB=800MPa level, (Fe-Ga0.15-Al0.05)99.0-Nb0.5-C0.5 sample showed λmax=60ppm, σB=730MPa level, and (Fe-Ga0.15-Al0.05)99.0-Mo0.5-C0.5 sample showed λmax=90ppm and tensile stress σB=780MPa level. The compressive stress effect to magnetostriction in some alloy will also investigated. As magnetostrictive alloy with high tensile strength like an 800MPa was not yet reported up to the present, those materials developed here will have a potential of industrial applications such as actuator and sensor, for example, transducer, and force sensor under severe environment.
V2: Multfunctionals and Multiferroics
Session Chairs
Hiroshi Asanuma
Yasubumi Furuya
Monday PM, December 01, 2008
Commonwealth (Sheraton)
11:30 AM - V2.1
Investigation of Surface und Bulk Properties of Ni2MnGa via X-ray Absorption Spectroscopy (XAS) and X-ray Magnetic Circular Dichroism (XMCD).
M. Kallmayer 1 , P. Poersch 1 , T. Eichhorn 1 , G. Jakob 1 , H. Elmers 1 , C. Jenkins 2 , C. Felser 2 , R. Ramesh 3 , M. Huth 4
1 Institut für Physik, Johannes Gutenberg-Universität Mainz, D-55128 Mainz Germany, 2 Institut für Anorganische und Analytische Chemie, Johannes Gutenberg-Universität Mainz, D-55128 Mainz Germany, 3 Department of Materials Science & Engineering, University of California, 94720 Berkeley, California, United States, 4 Physikalisches Institut, Goethe-Universität Frankfurt/Main, D-60438 Frankfurt/Main Germany
Show Abstract11:45 AM - V2.2
Growth and Structure of Epitaxial Ni-Mn-Ga Magnetic Shape Memory Films.
Gerhard Jakob 1 , Tobias Eichhorn 1 , Catherine Jenkins 1 2 3 , Peter Poersch 1 , Hans-Joachim Elmers 1 , Claudia Felser 2 , Ramamoorthy Ramesh 3 , Michael Huth 4
1 Institute of Physics, University of Mainz, Mainz Germany, 2 Institute for Anorganic and Analytical Chemistry, University of Mainz, Mainz Germany, 3 Department of Materials Science & Engineering, University of California, Berkeley, California, United States, 4 Physics Institute, University of Frankfurt, Frankfurt Germany
Show AbstractNew perspectives for magnetically induced actuation have been opened by the discovery of huge magnetic field induced strain in Ni2MnGa and related compounds. An alignment of the crystallographic axes with respect to the magnetic field direction is required in order to achieve maximum strain. As thin films are clamped to the substrate, epitaxial free standing films are finally required. We prepared Ni2MnGa films by sputtering from compound targets onto heated single crystalline substrates. As target materials we used the stoichiometric compound Ni2MnGa, delivering films with the martensite transition below room temperature, and a manganese rich target (Ni1.96Mn1.22Ga0.82). Sputtering from the latter resulted in martensite temperatures above 100°C. Epitaxial growth was achieved on a variety of substrates among them MgO(100), Al2O3(11-20), and BaF2(111) yielding films with different out of plane orientations switching from (100) to (110) to (111), respectively. In all cases four circle diffractometry proved the epitaxial in plane orientation. Temperature dependent x-ray diffraction was used to correlate the structural transition with anomalies in the temperature dependent magnetization and electrical transport. High substrate temperatures were beneficial in order to achieve high saturation magnetization. Four circle diffraction showed the films being in the martensite state at room temperature to possess a 7-fold superstructure. This is evident by superlattice lines in x-ray diffraction. The splitting in different variants can also be reconstructed from the intensity distribution in reciprocal space.With respect to free standing films we prepared highly textured films on water soluble single crystalline NaCl substrates. The in-plane orientation shows two epitaxial variants to coexist. Another way to free standing cantilevers was using a focussed ion beam system to cut free standing cantilevers. With optical microscopy and atomic force microscopy we observed the martensite twinning structure and its evolution during the transition. A partial magnetic field induced movement of the twin boundaries in the free standing cantilevers was observed using atomic force microscopy. Annealing experiments to release the blocking stress are in progress.
12:00 PM - V2.3
Magnetostriction in Fe-Co Binary Probed Using the Thin Film Composition Spread Technique.
Dwight Hunter 1 , R. Takahashi 1 , R. Suchoski 1 , J. Hattrick-Simpers 1 , S. Lofland 2 , M. Wuttig 1 , I. Takeuchi 1
1 Department of Materials Science and Engineering, University of Maryland, College Park, Maryland, United States, 2 Department of Physics and Astronomy, Rowan University, Glassboro, New Jersey, United States
Show AbstractPrevious investigation of the Fe-Ga binary system using the combinatorial approach showed that this technique can be used successfully to capture bulk trends of magnetostriction as a continuously changing function of composition [1]. Here, the combinatorial technique was applied in the study of magnetostriction in Fe-Co thin film samples. The films with continuously varying composition were deposited at room temperature using a magnetron co-deposition system onto a micro-fabricated array of cantilevers on a Si wafer. Using an optical high-throughput measurement system, the change in magnetostriction across the Fe-Co phase diagram was obtained by systematically monitoring the deflection of each cantilever. The values of magnetostriction as a function of composition mirrors the bulk trend [2] in which the striction rises to two maxima, one at Fe50Co50 composition and the other spanning over the range between 19 and 27 atomic % of Fe. Microstructural analysis of synchrotron microdiffraction data indicates that the nanocrystal grains are randomly oriented polycrystalline films. In conjunction with annealing experiments, [3] the results suggest that the maximum striction observed in the Co-rich region might be due to a structural transition occurring close to the bcc/(hcp+fcc) phase boundary. It may be suspected that the peak of the magnetostriction in the Co-rich region is of similar origin as the one reported in Fe-Ga [4] where the maximum striction occurs at the bcc/DO3 and DO22/DO19/ L12/bcc boundaries. Results of mapping of magnetostriction for other systems will also be discussed. [1] Hattrick-Simpers, et al., “Combinatorial Investigation of Magnetostriction in Fe-Ga and Fe-Ga-Al”, to be published.[2] Y. Masiyama, Sci. Rpts. of Tohoku Imperial U., 21, 394 (1932).[3] M. Wuttig and L. Dai, Scripta Mat., to be published.[4] G. Petculescua, et al., J. Appl. Phys. 97, 10M315 (2005).This project was funded by ONR-MURI N000140610530.
12:15 PM - V2.4
Magnetoelastic Material as a Biosensor for the Detection of Salmonella Typhimurium.
Ramji Lakshmanan 1 , Rajesh Guntupalli 4 1 , Shichu Huang 1 , Michael Johnson 1 , Leslie Mathison 1 , I-Hsuan Chen 3 , Valery Petrenko 2 , Zhong-Yang Cheng 1 , Bryan Chin 1
1 Materials Engineering, Auburn University, Auburn, Alabama, United States, 4 Department of Anatomy, Physiology and Pharmacology, College of VetirinaryMedicine, Auburn University, Auburn, Alabama, United States, 3 Department of Biological Sciences, Auburn Unviersity, Auburn, Alabama, United States, 2 Department of Pathobiology, College of VetirinaryMedicine, Auburn University, Auburn, Alabama, United States
Show AbstractMagnetoelastic materials are amorphous, ferromagnetic alloys that usually include a combination of iron, nickel, molybdenum and boron. Magnetoelastic biosensors are mass sensitive devices comprised of a magnetoelastic material that serves as the transducer and bacteriophage as the bio-recognition element. By applying a time varying magnetic field, the magnetoelastic sensor thin films can be made to oscillate, with the fundamental resonant frequency of oscillations depends on the physical dimensions and properties of the material. The change in the resonance frequency of these mass based sensors can be used to evaluate the amount of analyte attached on the sensor surface. Filamentous bacteriophage specific to S. typhimurium was used as a bio-recognition element in order to ensure specific and selective binding of bacteria onto the sensor surface. The sensitivity of magnetoelastic materials is known to be dependent on the physical dimensions of the material. An increase in sensitivity from 159Hz/decade for a 2mm sensor to 770Hz/decade for a 1mm sensor and 1100Hz/decade for a 500micron sensor was observed. The sensors were characterized by scanning electron microscopy (SEM) analysis assayed biosensors to provide visual verification of frequency responses and an insight into the characteristics of the distribution of phage on the sensor surface. The magnetoelastic sensors immobilized with filamentous phage are suitable for specific and selective detection of target analyte in different media. Certain modifications to the measurement circuit resulted in better signal to noise ratios for sensors with smaller dimensions (L<1mm). This was achieved by tuning the circuit resonance close to that of the sensor. According to models and preliminary tests, this method was anticipated in about a 5 times increase in signals for a 200×40×6microns. This technique and further studies into the design and modification of the measurement circuits could yield better, sensitive responses for sensors with smaller dimensions. The magnetoelastic materials offer further advantages of potential miniaturization, contact-less nature and ease of operation.
V3: Sensors and Novel Processing
Session Chairs
Shanyi Du
Frederic Dumas Bouchiat
Atulasimha Jayasimha
Jinsong Leng
Monday PM, December 01, 2008
Commonwealth (Sheraton)
2:30 PM - V3.1
Fabrication of Gas Nanosensors and Microsensors via Local Anodic Oxidation.
Braulio Archanjo 1 , Guilherme Silveira 1 , Alem-Mar Goncalves 1 , Diego Alves 1 , Andre Ferlauto 1 , Rodrigo Lacerda 1 , Bernardo Neves 1
1 Physics, UFMG, Belo Horizonte Brazil
Show AbstractA new nanosensor, and microsensor, fabrication method, employing scanning probe microscopy (SPM) and local anodic oxidation (LAO), is demonstrated. Two different metal oxides (MoOx and TiOx) are employed as proof-of-concept materials, producing sensors with suitable response and sensitivities down to low concentrations of both reducing and oxidizing gases. Using conventional optical lithography, a thin metal track (Mo or Ti), with electrical contacts, is patterned. The active region of the sensor is directly fabricated onto the track via SPM-assisted LAO, creating nano- and micro-scale metal oxide (MoOx or TiOx) structures, finalizing the sensor fabrication. Two distinct LAO routes, a slow (conventional) and a fast (unusual) one, are employed to produce nano- and micro-sensors, respectively, which are tested at different temperatures using CO2 and H2 as test gases. Sensitivities down to ppm levels are demonstrated and, in principle, this methodology, including both slow and fast LAO routes, could be applied to any desired metal or metal alloys, further extending sensing possibilities of designed nano- and micro-devices. Finally, this novel sensor design and fabrication concept is proposed on a way that it could be readily implemented in conventional industrial microfabrication processes.
2:45 PM - V3.2
Controlled Assemble and Microfabrication of Zeolite Nanoparticles on SiO2 Substrates for Potential Biosensor Applications.
Seckin Ozturk 1 4 , Kubra Kamisoglu 2 , Rasit Turan 1 3 , Burcu Akata 1 4
1 Micro and Nanotechnology, Middle East Technical University, Ankara Turkey, 4 Central Laboratory, Middle East Technical University, Ankara Turkey, 2 Chemical Engineering, Middle East Technical University, Ankara Turkey, 3 Physics, Middle East Technical University, Ankara Turkey
Show AbstractThe development of new fabrication methods of organized nanoparticles on surfaces is important for electronic, optoelectronic, biological, and sensing applications. Usually chemical modification of SiO2 substrates with silanization techniques are used for potential biosensor and electronic applications where the targeted biological components are assembled onto the modified substrates. By combining silanization methods with microfabrication technology, surfaces can be patterned with functional groups, making it possible to attach cellular structures such as microtubules or cells in specific locations.In such components, there is a great need to increase the sensitivity level of the fabricated device, and one way to achieve this can be done via further assembly of nanoparticles on the modified substrates which show promising characteristics for the immobilization of the targeted chemical/biological compounds. Zeolite nanoparticles were shown to display good interactions with biological molecules. They have remarkably large surface area that is available for the immobilization of different molecules, tunable surface properties for controlled variation of surface charge and hydrophilic/hydrophobic characteristics. The zeolite monolayers are suggested to be used as ideal media for organizing semiconductor quantum dots and nonlinear optical molecules in uniform orientations.In the current study, zeolite nanoparticles were organized into functional entities on silanized SiO2 substrates and microfabricated using the electron beam lithography (EBL). The effect of different silanization compounds and different techniques for zeolite assembly on the silanized surfaces were investigated. For that purpose, different experimental procedures and parameters were investigated to efficiently assemble zeolite crystals on SiO2 substrates. Spin-coating (SC) and ultrasound aided strong agitation (US) methods were tested using silanized zeolite micron- and nanoparticles. Both methods were facile in terms of experimental approach. Full coverage of the substrate was obtained after both methods, however strong agitation (US) leads to better organization of zeolite micro and nanocrystals. Furthermore, the obtained zeolite micropatterns formed on the Si wafer substrate were more fully covered upon using the silanized zeolite nanoparticles.
3:00 PM - V3.3
Growth of One-Dimensional Metal Oxide Nanostructures and Nanowire-based Devices.
Sanjay Mathur 1 2 , Sven Barth 2 , Francisco Hernandez-Ramirez 3 , Joan Daniel Prades 3 , Albert Romano-Rodriguez 3
1 Institute of Inorganic Chemistry, University of Cologne, Cologne Germany, 2 Department of CVD-Technology, Leibniz-Intitut für Neue Materialien, Saarbrücken Germany, 3 IN2UB and EME-Department of Electronics, University of Barcelona, Barcelona Spain
Show AbstractMonday 12/1New Presenter V3.3 @ 2:00 PMGrowth of One-Dimensional Metal Oxide Nanostructures and Nanowire-based Devices. Sven Barth
3:15 PM - V3.4
Catalyst-based Solid State Sensor Schemes for Wide Temperature Range Hydrogen Leak Detection.
Claudiu Muntele 1 , Sandra Sadate 1 , Malek Abunaemeh 1 , Cydale Smith 1 , Daniel McElhaney 1 , Jonathan Gardner 2 , Abdalla Elsamadicy 2 , Daryush Ila 1
1 , Alabama A&M University, Normal, Alabama, United States, 2 , University of Alabama in Huntsville, Huntsville, Alabama, United States
Show AbstractSilicon carbide based non-linear electronics devices (MOSFET, metal-semiconductor, or p-n junctions) are promising candidates for hydrogen detection schemes if used in conjunction with a good catalyst from the platinum group of elements. For the past decade, the emphasis was mostly on high temperature applications in the automotive (for hydrogen-fueled engines) and in the aerospace industry (for jet engines), but now the focus is broadening to include auxiliary systems such as storage tanks, fuel lines, fuel production systems, all operating in a wide range of temperatures, from ambiental (RT – room temperature) to cryogenic. Hydrazine is a particular hydrogen-containing chemical of interest, as is widely used as a fuel in rocket propulsion systems, fuel cells, pesticides, dyes etc. It is also a neurotoxin, causing damage to most organs in the human body. Therefore sensors able to detect hydrazine leaks at sub-ppm level at RT (anhydrous hydrazine melts at 2 °C and evaporates at 113.5 °C) and in a wide humidity range (hydrazine is fully miscible in water) are highly desirable. Sensitive analytical methods have been developed for the determination of hydrazine in air, water, food, drugs, and cigarette smoke. However, all these methods involve complicated analytical instrumentation generally available only in a specialized laboratory environment. From the variety of detection schemes available for portable devices, two seem of being the most commonly used: color-changing paper readers (e. g. MDA 7100 and newer) and fuel cell-based detectors (e. g. products of PureAire Monitoring Systems, Inc.).While high temperature operation is completely characterized for catalyst-based sensors, low temperature operation presents catalyst-related challenges (such as catalyst “poisoning” due to surface passivation), some of them little understood, some well characterized but without a functional solution. In this paper we are addressing, on a comparative basis, solutions to challenges associated with using catalysts as active agents in capacitive, non-linear (p-n structures), and linear (resistors) hydrazine and hydrogen detection schemes in a temperature range from 77 K (liquid nitrogen) to 400 K. We used e-beam deposition and low energy ion implantation for preparing our samples, and current vs. voltage electrical measurements to monitor the devices’ response to hydrazine and hydrogen. Raman spectroscopy was used for investigating the surface chemistry of the devices exposed to hydrazine at various temperatures.
3:30 PM - **V3.5
Guided Self-assembly of Nanostructured Titanium Oxide.
Baoxiang Wang 1 , Min Zhou 1 , Zbigniew Rozynek 1 , Jon Otto Fossum 1
1 Department of Physics, Norwegian University of Science and Technology, Trondheim Norway
Show AbstractElectrorheological fluid (ERF), as a smart materials, are suspensions of polarized dielectric particles in a nonconducting liquid and exhibit drastic changes in their rheological properties, which include a large increase in apparent viscosity and the formation of reversible suspension microstructures. Application of an electric field can induce polarization of the suspended particles. As a result, a chainlike structure can be formed along the electric field direction in a few milliseconds.1-5 So the shape and surface of particle may play a very important role to for the assembly of chainlike structure. Titanium oxide nanowires and nanorods are synthesized by a simple wet chemical method and characterized by the SAXS, AFM, and thermal analysis. Firstly, Tetrabutyl titanate (TBT) precursor was added to ethylene glycol (EG) and heated to form TiOx nanowires.6 Furthermore, TiOx nanorods with high rough surface can be got by hydrolysis of TBT with the help of Cethyl-Trimethyl-Ammonium Bromide (CTAB) as surfactant in EG solution. AFM results show that the nanowires are easy aggregating each other to form boudles and high rough TiOx nanorods is formed by the self-assembly of TiOx nanospheres. The electrorheological (ER) effect is investigated with the suspension of titanium oxide nanowires or nanorods dispersed in silicone oil. Oil suspensions of titanium oxide nanowires or nanorods exhibit a dramatic assembly when submitted to a strong DC electric field and aggregate to forms chains like structures along the direction of applied electric field. We have used small angle X-ray scattering to get insight into the nature of the titanium oxide nanowires and nanorods in the chains. The two-dimensional SAXS images from chains of anisotropic shape particles exhibit a marked anisotropy SAXS patterns, reflecting the preferential guided selfassembly of the particles in the field.
4:30 PM - **V3.6
Development Of Multifunctional Structural Material Systems By Innovative Design And Processing.
Hiroshi Asanuma 1
1 Mechanical Engineering Course, Chiba University, Chiba-shi Japan
Show AbstractInnovative designing concept and fabrication process to realize smart and robust structural material systems, (1) without using sophisticated functional materials (Type A) and (2) using them in a metallic matrix as a protective environment (Type B), respectively, are introduced in this paper. The Type A route can be explained as follows: There exist a couple of competitive structural materials which normally compete with each other because of their similar and high mechanical properties, and they tend to have another property which is different from each other or opposite among them. So if they are combined together to make a composite, the similar property, normally high mechanical property, can be maintained, and the other dissimilar property conflicts with each other, which will successfully generate a functional property without using any sophisticated functional materials. As successful examples of this type, Ti fiber/Al multifunctional composites and CFRP/aluminum active laminates have been developed. The second one (Type B) can be realized by embedding fragile functional fibers in an aluminum matrix by the interphase forming bonding method developed by the author, and piezoelectric ceramic fiber/aluminum composites and optical fiber sensor/aluminum composites have been successfully fabricated.
5:00 PM - V3.7
Nanoimprinting using Anodic Porous Alumina as a Mold.
Takashi Yanagishita 1 2 , Takahide Endo 1 , Kazuyuki Nishio 1 2 , Hideki Masuda 1 2
1 , Tokyo Metropolitan Univ., Tokyo Japan, 2 , KAST, Kanagawa Japan
Show AbstractThe preparation of nanometer scale structures has attracted much attention due to the utilization for various types of functional application fields. Nanoimprinting is a promising technique for the high-throughput preparation of ordered fine structures on a substrate. The molds used for nanoimprinting are usually fabricated by a combination of electron beam lithography and the dry etching. However, in these processes, it is difficult to prepare the molds with a pattern of high aspect ratios or large sizes. In our previous reports, we described the fabrication of polymer nanostructures with high aspect ratios by nanoimprinting using anodic porous alumina as a mold [1-4]. Anodic porous alumina, which is formed by anodization of Al in an acidic solution, is a promising for the molds to prepare the nanometer-scale structures with high aspect ratios and large sizes, because of its unique geometrical structures [5]. In the present report, we describe the preparation of ordered structures of inorganic materials with high aspect ratios by nanoimprinting using anodic porous alumina as a mold. In the experiment, ordered silica pillar arrays were prepared by nanoimprinting using a spin-on-glass solution. The diameter and height of silica pillars could be controlled by changing the geometrical structures of anodic porous alumina molds. The obtained silica nanopillar arrays will be applied to various types of functional nanodevices.[1] H. Masuda et al., Appl. Phys. Lett., 78, 826 (2001). [2] T. Yanagishita et al., Jpn. J. Appl. Phys. 45, L804 (2006). [3] T. Yanagishita et al., Vac. Sci. Technol. B, 25, L35 (2007). [4] T. Yanagishita et al., Appl. Phys. Exp., 1, 067004 (2008). [5] H. Masuda et al., Science, 268, 1466 (1995).
5:15 PM - V3.8
Multiple Duplication of Electroformed Nano-Ni Stamps from Si Mother Mold.
Si-Hyeong Cho 1 , Jung-Ki Lee 1 , Jung-Ho Seo 1 , Hyun-Woo Lim 2 , Jin-Goo Park 1 2
1 Bio-Nano Technology, Hanyang University, Ansan city, Gyeonggi-do, Korea (the Republic of), 2 Materials Engineering, Hanyang University, Ansan city, Gyeonggi-do, Korea (the Republic of)
Show AbstractNanoimprint lithography (NIL) is an alternative lithographic method that offers a sub-10 nm feature size, high throughput, and low cost. It requires a mold which has a low fabrication cost and long life time. A stamp is the material with various patterns to transfer on the plastic substrate. Materials such as Si, quartz, plastic and Ni have been widely used for micron or sub micron sized stamp fabrication depending on its pattern size and application. Si and quartz are very easy to be broken, and plastic can be deformed easily during process. However, Ni has high enough hardness and life time as a mold material and can be fabricated from on Si micro to nano sized molds with a seed layer by a simple Ni electro-deposition. After electro-deposition, the sample is usually dipped in KOH solution to remove Si from Ni. The consumption of Si mold is necessary step to produce a Ni stamp.In this study, a method was developed to fabricate a Ni stamp without the consumption of Si stamp. Vapor SAM (self assembled monolayer) method was used to deposit hydrophobic layer on Si mold. A low surface energy release layer on stamp surfaces not only helps to improve imprint qualities, but it also increases the stamp lifetime significantly by preventing surface contamination. Hydrophobic layer, which has a low surface energy, makes possible to separate Ni from Si substrate without causing any damages on Si stamp. The characteristics of deposited hydrophobic layer were analyzed by measurements of the contact angle, its hysteresis, surface energy, thickness and lateral friction force. The stiction of Ni on Si mold was observed when the separation of Ni from Si was tried without the SAM deposition.The multiple duplication of Ni stamps has been successfully developed without disposing costly Si mother stamp. Duplicated patterns on Ni stamp showed the same patterns as on Si mother mold when they were observed with optical microscope, FE-SEM, and AFM (atomic force microscope).
5:30 PM - V3.9
A Novel Technique for the Nano-fabrication of Diamond Stamp Structures.
Warren McKenzie 1 , Graham Cross 1 , John Pethica 1
1 CRANN, Trinity College Dublin, Dublin Ireland
Show AbstractA novel process for the fabrication of complex nano–scaled patterns on flat single crystal diamond surfaces has been developed*. These patterned surfaces could potentially be used as a stamp for the highly reproducible fabrication of nano-electronic circuits via the established techniques nano-imprint lithography or hot embossing. This process utilizes facilities common to most microelectronic laboratories and, on-average, takes approximately one hour to reproduce a complex nanoscaled pattern over an area ~5000µm2. Given the simplicity and efficiency of the process, this technique could easily be adapted for the fabrication of nano-scaled patterns over larger (mm – cm) scaled diamond surfaces.*Note to examiners or conference organizers - this abstract is purposely vague and withholds most of the critical information relating to the subject. This technique will be the subject of a patent application to be filed the week of 30th June 2008. After this time the abstract (and presentation) can be amended to include all relevant details .
5:45 PM - V3.10
Fabrication of PbTe and PbTe@Pb(OH)2 Core-shell Nanocubes and Their Self-Assembly.
Jun Zhang 1 , Jiye Fang 1
1 , State University of New York at Binghamton, Binghamton, New York, United States
Show AbstractSelf-assembly of nanocrystals has attracted increasing attention. However, the fabrication of nanocubic building-block-containing assembly pattern has remained a challenge and requires a precise control in both the size and shape. For identical spheres, both the hexagonal close-packing and cubic close-packing give the highest packing efficiency, 74.04%, whereas nanocrystals as the building blocks could be present in various shapes such as octahedrons and cubes. The preparation of an assembly containing nanocubes can achieve a packing density of as high as 100% if the interparticle spacing is neglected. In this presentation, we report our recent progress in synthesis of PbTe nanocubes and PbTe@Pb(OH)2 core-shell nanocubes through a wet-chemical processing approach. We also present the structural investigation on these self-assembled patterns as well as various characterizations we have performed, including XRD, TEM, and SAXRD. Optical investigation will also be discussed.
V4: Poster Session I
Session Chairs
Tuesday AM, December 02, 2008
Exhibition Hall D (Hynes)
9:00 PM - V4.1
X-Ray-Induced Wettability Modification.
Yong Bum Kwon 1 , Byung Mook Weon 1 , Kyu Hwang Won 1 , Jung Ho Je 1 , Yeukuang Hwu 2 , Giorgio Margaritondo 3
1 , X-ray Imaging Center, Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang Korea (the Republic of), 2 , Institute of Physics, Academia sinica, Taipei Taiwan, 3 , School of Basic Sciences, Ecole Polytechnique Fádárale de Lausanne, Lausanne Switzerland
Show AbstractLight-induced wettability modification is an important surface phenomenon throughout nature and technology (1). In particular ultra violet (UV)-induced wettability modification of inorganic materials such as ZnO and TiO2 has been widely studied (2, 3) owing to advantages of remote controllability and individual addressability. However UV-induced wettability modification remains a challenge for applications because of long recovery time from slow chemical kinetics, and thus has a limitation to UV-specific materials. For fast response or recovery time, charging-induced wetting using an e-beam source in vacuum was suggested as a possible trigger source for inorganic materials (4). In this study we suggest a fast, reversible strategy that is adoptable in air by using an irradiation of X-rays, universally ionizing inorganic materials. We reveal that X-ray-induced wettability modification occurs in a variety of inorganic materials, for instance, Si, ZnO, ZnS, TiN, SrTiO3, and Al2O3. In particular a rapid response dynamics of ~10 min (e.g., ZnS, ZnO, and SrTiO3) is visible and is attributed to a fast charging by X-ray irradiation. Meanwhile a fast recovery time of ~50 min (e.g., ZnO) is obtained owing to discharging mechanism, whereas that is very slow (several tens of hours) for UV-induced transition. Contact angle and surface potential measurements show detailed dynamics and localization of charging and discharging by X-ray irradiation. We suggest a feasible wettability modification using X-ray-induced charging to extend the applications of inorganic materials.References:(1) R. Wang, et al. Nature 388, 431 (1997).(2) R. Sun, et al. J. Phys. Chem. B 105, 1984 (2001).(3) X. Feng, et al. J. Am. Chem. Soc. 126, 62 (2004).(4) D. Aronov, et al. Appl. Phys. Lett. 90, 104104 (2007).
9:00 PM - V4.10
Indium Tin Zinc Oxides Composites Thin Films for Multifunctional Sensors.
Rajini Konda 1 , Alex Lee 2 , Rajeh Mundle 1 , Olu Bamiduro 1 , Gilbert Kogo 1 , Ozgul Yasar 1 , Messaoud Bahoura 1 , Frances Williams 1 , Aswini Pradhan 1
1 Center for Materials Research, Norfolk State University, Norfolk, Virginia, United States, 2 Chemical Engineering, Virginia Tech, Blacksburg, Virginia, United States
Show Abstract9:00 PM - V4.11
Technique for High-resolution Imaging of Local Lattice Distortion in LSIs by Forbidden Reflection-based Dark-field Transmission Electron Microscopy.
Shiro Takeno 1 , Mitsuo Koike 1 , Hiroki Tanaka 1 , Teruyuki Kinno 1 , Mitsuhiro Tomita 1 , Fumihiko Uesugi 2
1 , Toshiba Corporation, Yokohama Japan, 2 , Toshiba Nanoanalysis Corporation, Yokohama Japan
Show AbstractTechniques for precise measurement of local stress (or lattice distortion) in LSIs or nanoscale systems are indispensable for investigating failure mechanisms and significant for the development of reliable devices. In silicon crystal, critical resolved shear stress is fairly low, i.e., around a few MPa for a certain glide system [1], and imaging of stress field at a microscopic level in LSIs, especially in interfacial regions, has been an important research target. In previous transmission electron microscopy (TEM)-based imaging techniques, diffraction contrast analysis of bright- and/or dark-field images has been tried for stress analysis [2-4]. These studies were based on two-beam conditions that are assumed to be a cause of insufficient effective spatial resolution since the conditions require a high-angle tilting operation to the interfaces of interest in LSIs. (Effective spatial resolution represents the practical resolution for the tilted conditions.) Recently, we proposed a straightforward and sensitive imaging technique for local lattice distortion in an area of hundreds of nanometers in conjunction with the stress relaxation during the TEM specimen foil preparation for Si and related crystals [5,6]. The proposed technique is based on the observation of dark-field image (DFI) formed by a forbidden reflection (FR) under a specific beam incidence condition. (We abbreviate our proposed method to FR-DFI.) The relaxation causes the local change of deviation parameter for a certain Bragg reflection sensitively [7], and FR-DFI is based on this characteristic phenomenon. We showed that the current best effective spatial resolution of FR-DFI was about 5.2 nm. In order to improve the effective spatial resolution in FR-DFI, we investigated the intensity distribution of 002-DFIs for SiGe/Si system under several experimental conditions such as TEM specimen thickness, incidence beam direction, and acceleration voltage of electron beam. In this presentation, we will show that the intensity distribution of 002-DFI is sensitively influenced owing to a subtle change of the thickness of TEM specimen foil, and the effective spatial resolution of less than 5 nm can be achieved for Si crystal by precise thickness control of the specimen foil. Appropriate experimental parameters for high-resolution FR-DFI observation and artifacts induced under the critical experimental condition as well as the basic concept of FR-DFI will be discussed in detail. (References)[1] S. M. Hu, J. Appl. Phys. 70 (1991) R53[2] D. D. Perovic et al., Philos. Mag. A64 (1991) 1[3] S. McKernan et al., Inst. Phys. Conf. Ser. 87 (1987) 201[4] J. Demarest et al., Appl. Phys. Lett. 77 (2000) 412[5] S. Takeno et al., Proc. 16th International Microscopy Congress (2006) 1480[6] S. Takeno et al., Surface and Interface Analysis (to be published)[7] U. Bangert et al., Philos. Mag. A59 (1989) 629
9:00 PM - V4.12
Hydrogen Sensing Properties in PdO Sputtered Thin Films.
Young Taek Lee 1 2 , Eunsong–yi Lee 2 , Da Hye Kim 2 , Kye Jin Jeon 2 , Wooyoung Lee 1 2
1 Nanomedical National Core Research Center, Yonsei University , Seoul Korea (the Republic of), 2 Department of Materials Science and Engineering, Yonsei University, Seoul Korea (the Republic of)
Show Abstract9:00 PM - V4.14
Hysteretic Resistance in Hydrogenated Pd Thin Films.
Eunsong-yi Lee 1 , Jun Min Lee 1 , Won Jin Choi 1 , Kye Jin Jeon 1 , Wooyoung Lee 1
1 Department of Materials Science and Engineering, Yonsei University , Seoul Korea (the Republic of)
Show Abstract9:00 PM - V4.15
In-Situ Characterization of Polymer films and Their Interactions with Environmental and Biological Substances by Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D).
Archana Jaiswal 1
1 , Q-Sense, Inc., Gleb Burnie, Maryland, United States
Show AbstractRecently, there has been an increasing demand of analytical tools for the characterization of interaction between biological molecules and polymeric materials due to its broad scientific interest and great commercial importance. Applications and products developed from this field of study include medical implants, drug delivery formulations, biosensors and biofilms. Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), a nanomechanical acoustic-based analytical technique, is a novel tool to analyze binding events and reactions occurring at a wide variety of biointerfaces. With QCM-D, simultaneous measurement of resonance frequency change (ΔF) and energy dissipation change(ΔD) is performed by periodically switching off the driving power of oscillation of the sensor crystal and recording the decay of damped oscillation as the adsorption and/or structural changes takes place at sensor crystal surface. While change in frequency provides information about mass changes, dissipation (D) provides structural information about the viscoelastic properties of adsorbed films in real time.In the present poster we show the real-time monitoring of hydration/solvation of polymer films in both liquid and gaseous environments, study of crosslinking of polymeric films, characterization of the incorporation and binding of proteins (and other molecules) to polymers, and characterization of polyelectrolyte multilayers at any time during their build-up process.
9:00 PM - V4.16
Multiple Phage-Based Magnetoelastic Biosensors System for the Detection of Salmonella typhimurium and Bacillus anthracis Spores.
Shichu Huang 1 , Hong Yang 1 , Ramji Lakshmanan 1 , Michael Johnson 1 , I-suan Chen 2 , Howard Wikle 1 , Valery Petrenko 3 , James Barbaree 2 , Bryan Chin 1
1 Materials Engineering, Auburn University, Auburn, Alabama, United States, 2 Dept. of Biological Sciences, Auburn University, Auburn, Alabama, United States, 3 Dept. of Pathobiology, Auburn University, Auburn, Alabama, United States
Show AbstractThe paper presented a multiple magnetoelastic (ME) biosensors system for in-situ detection of S. typhimurium and B. anthracis spores in a flowing bacterial/spore suspension (5×101 - 5×108 cfu/ml). ME biosensor was formed by immobilizing filamentous phage (specific to each detection target) on the ME platforms (2x0.4x0.015mm). An alternating magnetic field was used to resonate the ME biosensor to determine its resonance frequency. When cells/spores are bound to a ME biosensor surface, the additional mass of the spores causes a decrease in the resonance frequency of the sensor. The detection system was composed of a control sensor, an E2 phage sensor (specific to S. typhimurium) and a JRB7 phage sensor (specific to B. anthracis spores). The frequency response curves of the ME biosensors as a function of exposure time were then measured and the detection limits of the ME biosensor was observed to be 5x103 cfu/ml. The results show that the phage-based ME biosensors can detect multiple pathogens simultaneously and offer good performance, including good sensitivity and rapid detection. Additionally, the specificity of this detection system was evaluated by exposure to a flowing mixture of S. typhimurium in the presence of extraneous foodborne pathogens. The E2 phage biosensor was observed to respond to S. typhimurium only, verifying the high specificity of the phage immobilized biosensor.
9:00 PM - V4.17
Wireless Remote 2-D Strain Sensor using SAW Delay Line.
Toru Nomura 1 , Atushi Saitoh 2
1 Faculty of Engineering, Shibaura Institute of Technology, Tokyo Japan, 2 , Shibaura Institute of Technology, Tokyo Japan
Show AbstractSurface acoustic wave (SAW) devices offer many attractive features for applications as chemical and physical sensors. In this paper, we present a novel SAW strain sensor for radio frequency identification (RF-ID) and structural health monitoring. The strain SAW sensor is passive sensor that can be attached to a structure and then remotely interrogated though a wireless interfaces. SAW delay lines have been designed for measurement of strain. The changes in the structure results in a phase change of the SAW delay lines. Two delay lines were used to measure the two-dimensional strain. The two delay lines crossed each other at right angles on a single substrate. The phase change of the delay lines were measured as the sensor response.Moreover, the SAW sensor requires no internal power supply to operate. A wireless sensing system is also proposed for effective operation of the strain sensor. In addition, an electronic system for accurately measuring the phase characteristics of the signal wave from the passive strain sensor is proposed.The two SAW delay lines that cross each other at right angles with the central frequency of 50 MHz were fabricated on a 128 YX LiNbO3 substrate. Experimental results showed that the phase varied in proportion to the strain applied to the surface. The results also showed that the passive sensor was very effective to measure the strain in a wireless mode and it was found that the system is very suitable to health and safety monitoring of structure.
9:00 PM - V4.18
The Transient Response Modification of a MIS Hydrogen Sensor with Excimer Laser Processing.
Linfeng Zhang 1 , Sachin Thanawala 2 , Ratna Naik 3 , Gregory Auner 2
1 Electrical Engineering, University of Bridgeport, Bridgeport, Connecticut, United States, 2 Electrical and Computer Engineering, Wayne State University, Detroit, Michigan, United States, 3 Physics and Astronomy, Wayne State University, Detroit, Michigan, United States
Show AbstractMetal-insulator-semiconductor (MIS) type sensors have been developed for several decades and they are sensitive to hydrogen even low as 10 ppm. This type sensor works as a capacitor, the Capacitance-Voltage (CV) curve would shift in the presence of hydrogen. At a constant capacitance, the voltage shift is a function of hydrogen concentration. Usually, this type sensor is operated above room temperature for a quick response. However, a reverse transient response is observed at high temperature (more than 100 oC). To minimize this reverse transient is a challenge. In this study, a sensor with Pd-Ni/AlN/n-Si(111) structure was prepared through magnetron sputtering chamber and the Plasma Source Molecular Beam Epitaxy (PSMBE). Surface segregation of Ni was found and Al was oxidized on the surface of AlN through X-ray Photoelectron Spectroscopy (XPS). In the hydrogen response testing, no reverse transient and baseline shift was observed at 80 oC. However, reverse transient was obvious and always there at 120 oC. This phenomenon is most probably related to some slow mobility charges in AlN. An excimer laser was used to modify the metal alloy and metal/insulator interface. Arraies of micro-bumps (radius: 5 μm) were created on the device surface. Through the testing, the reverse transient disappeared except in the first hydrogen response from a refreshed sensor. Thus, the surface modification with excimer laser can improve the sensor response time. The mechanism of the effect of this laser processing on the sensor performance was discussed further.
9:00 PM - V4.19
Conformable Passive Sensors for Wireless Structural Health Monitoring.
Sharavanan Balasubramaniam 1 , Tarisha Mistry 2 , Niwat Angkawisittpan 2 , Jung-Rae Park 1 , Alkim Akyurtlu 2 , Tenneti Rao 2 , Ramaswamy Nagarajan 1
1 Plastics Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, United States, 2 Electrical & Computer Engineering, University of Massachusetts Lowell, Rehovot Israel
Show Abstract Currently, sensors for damage detection and non-destructive evaluation are fabricated using techniques like photolithography, inkjet printing or thermal spray and laser micromachining. The commercial success of these sensors, however, depends on their performance and ease of manufacture. The application of conductive inks and pastes for wireless sensing with simple fabrication methods is an attractive proposition. Silver inks based on flaky powder and nanoparticles are very popular in the area of printed electronics due to their high electrical conductivity and environmental stability. Fabrication of sensors using binder-free inks, which can form pure metallic patterns (without leaving any non-metallic residue), will lead to devices with high quality factors and improved detection capabilities. Here, we present a novel binder-free, electrically conductive formulation that can be screen-printed to fabricate conformal sensors for wireless interrogation. On curing, these particulate metal pastes transform into continuous, conductive patterns at temperatures as low as 135C. Resonant inductor-interdigital capacitor circuits are screen-printed on polyester films to yield flexible LC sensors. The RF response of the LC sensors is measured using a vector network analyzer. Physical deformation or fracture of the conductive elements results in a detectable change in the RF response. The development and characterization of the conductive patterns and sensors as well as their wireless interrogation will be presented.
9:00 PM - V4.20
Study the Conduction Mechanism and the Electrical Response of Strained Nano-thin 3C-SiC Films on Si used as Surface Sensors.
Ronak Rahimi 1 , Chris Miller 1 , Alan Munger 1 , Srikanth Raghavan 1 , Charter Stinespring 2 , Dimitris Korakakis 1
1 Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, West Virginia, United States, 2 Chemical Engineering, West Virginia University, Morgantown, West Virginia, United States
Show AbstractVarious superior properties of SiC such as high thermal conductivity, chemical and thermal stability and mechanical robustness provide the basis for electronic and MEMS devices of novel design [1]. This work evaluates heterostructures that consist of a few nanometers-thin 3C-SiC films on silicon substrates. Nano-thin SiC films differ significantly in their electrical behavior compared to the bulk material [2], a finding that gives rise to a potential use of these films as surface sensors. To gain a better understanding of the effect of surface states on the electrical response of thin, strained films, these structures have been examined under variable conditions. Gas source molecular beam epitaxy has been used to grow nano-thin 3C-SiC layers on silicon substrates. Reflection high-energy electron diffraction patterns obtained from several 3C-SiC films indicate that these films are strained nearly 3% relative to the SiC lattice constant. Al, Cr and Pt contacts to a nano-thin film 3C-SiC were deposited and characterized. I-V measurements of the strained nano-thin films demonstrate metal-semiconductor-metal characteristics. Band offsets due to biaxial tensile strain introduced within the 3C-SiC films were calculated and band diagram incorporating strain effects have been simulated. Electron affinity of 3C-SiC has been extracted from experimental I-V curves and is in good agreement with the value which has been calculated for a strained 3C-SiC film [3]. Eventually, on the basis of experimental and simulation results, an empirical model for the current transport has been proposed. Fabricated devices have been characterized in a controlled environment under hydrogen flow and also in a reactive ambient, while heating the sample and oxidizing the surface, to investigate the effects of the environment on the surface states. Observed changes in I-V characteristics suggest that these surface-like, nano-thin films can be used as surface sensors.[1] Azevedo R G, Jones D G, Jog A V, Jamshidi B, Myers D R, Li Chen, Xiao-an Fu, Mehregany M, Wijesundara M B J and Pisano A P 2007 IEEE Sens. Jour. 7 568 [2] Hsieh WT, Fang Y K, Wu K H, Lee W J, Ho J J and Ho C W IEEE Trans. Electron Devices 2001 48 801-803 [3] Choyke W J, Feng Z C and Powell J A Jour. of Appl. Phys 1988 64 3163
9:00 PM - V4.21
Carbon Nanofiber-Network Sensor Films for Strain Measurement in Composites.
Nguyen Nguyen 1 , SangYoon Lee 1 , Nikhil Gupta 1
1 Mechanical and Aerospace Engineering, Polytechnic University, Brooklyn, New York, United States
Show AbstractConducting sensor films and coatings, comprising carbon nanofibers in epoxy resin, are developed for structural health monitoring of materials. The carbon nanofibers are present as a random network in these sensors. Applied stress or stain can increase or decrease the connectivity of fibers in the network leading to a change in the resistance of the film. Hence, the resistance of the film can be calibrated with respect to the applied stress and these films can be used as sensors. The fabricated sensors are calibrated for voltage drop across a fixed length on the film surface for the applied voltage in the range of 0-10 v. The input and output voltage show a linear relationship. The ratio of the output to the input voltage, defined as efficiency, is between 10-20% depending on the volume fraction of carbon fibers in the film and is a factor in determining the sensitivity of the sensor film. It was observed that the films show low output efficiency because the nanofibers are coated with a coupling agent resulting in their significant wetting with the matrix resin, which increases the contact resistance. Therefore, a process is developed to decrease the contact resistance between nanofibers by embedding them in the resin as a network. The dispersion as a network shows remarkable improvement in the output efficiency to 30-50%. The sensor films are attached to the surface of glass fabric/epoxy matrix laminates and calibrated under three-point bending conditions. The films are attached on the tensile side of the specimen using an epoxy based adhesive. Due to the applied strain the connectivity of nanofiber network changes and the resistance of the film increases. The change in conductivity is calibrated with respect to the applied force. The films were calibrated for five loading cycles and the results are found to be repeatable, showing that these sensors can be used for multiple loading cycles. Nanofiber reinforced epoxy based coatings are also developed and applied as paints to the surface of laminates. These coatings are also tested for conductivity and calibrated for measurement of strain in the laminates. The results for coating are similar to those observed for films. The results show that the nanofiber based sensors have higher efficiency, lower cost, and better tailorability than similar sensors based on carbon nanotubes. The results show that such sensing schemes can be effectively used for structural health monitoring of composite materials.
9:00 PM - V4.22
Influence of Oxygen Partial Pressure on the Physical Properties of Titanium Oxycarbide Thin Films: The Influence of Composition, Bonding Characteristics and Structural Evolution.
Senentxu Lanceros-Mendez 1 , A. Fernandes 1 , J. Serrado Nunes 1 , F. Vaz 1 , A. Pinto 2 , N. Martin 3
1 Physics, Universidade do Minho, Braga Portugal, 2 , Universidade do Minho, Guimarães Portugal, 3 , Institut FEMTO-ST, UMR 6174, CNRS UFC ENSMM UTBM France
Show AbstractThis work is devoted to the investigation of multifunctional titanium oxycarbide, TiCxOy, films prepared by dc reactive magnetron sputtering. Films can be produced with tailor made electrical and optical properties, opening enormous potential for smart system integration. The electrical properties of the films deposited on glass and silicon substrates have been investigated and discussed in relation with their chemical composition and crystalline structure. The effects of the oxygen content on the composition and crystallographic structure were investigated by EMPA, XRD and resistivity measurements. The color of the films changed from metallic tone, for films produced with low oxygen content (< 40 at. %), changing to a very bright yellow-pale and brown colors, to films with an intermediate oxygen content, and finally for higher oxygen content (> 68 at. %) the films present interference color (rainbow-like appearance). This change in optical behavior from opaque to transparent (characteristic of a transition from metallic to insulating-type materials), promoted by the change in the oxygen flow rate (variation in the coatings composition), revealed that significant changes were occurring in the films structure and electronic properties thus opening new potential applications for the films, beyond those of purely decorative ones. Taking this into account, the electrical behavior of the films was investigated as a function of the oxygen content and correlated with the observed chemical, electronic and structural features. The variations in composition disclosed the existence of three different zones, which were correlated to different compositions and the correspondent changes in crystalline structures. For the so-called metallic zone, X-ray diffraction revealed the development of films with a B1 NaCl face-centered cubic titanium oxycarbide-type phase, with some texture changes. Increasing the gas flow (oxygen amount), the structure of the films changed to oxide-type ones, TiO2 (anatase mostly), passing by an intermediate zone where the films are roughly amorphous. The composition/structure variations were consistent with the chemical bonding analysis carried out by X-ray Photoelectron Spectroscopy (XPS), which showed increasing amounts of O bonded to Ti. The electronic properties of the films exhibited significant changes from zone to zone. Resistivity measurements revealed a very wide range of values, varying from relatively high conductive materials (for metallic zone) to highly insulating films within the oxide zone. ACKNOWLEDGMENTThe authors thank the Portuguese Foundation for Science and Technology (FCT)- Grant PTDC/CTM/69362/2006.
9:00 PM - V4.23
Joining Technique for High Temperature Pb-free Solder by Using Vacuum Evaporation Deposition.
Toshihide Takahashi 1 , Tatsuoki Kono 1 , Shuichi Komatsu 2
1 Corporate Research & Development Center, Toshiba Corporation, Kawasaki, Kanagawa, Japan, 2 , Toshiba Research Consulting Corporation, Kawasaki, Kanagawa, Japan
Show AbstractHigh temperature solders are used as joining material for semiconductor chip to lead frame in power semiconductor devices. They are required to have a heat resistance of more than 533 K because they are heated up to 523 K in the reflow process for mounting the electronic components. Conventional solders have good heat resistance to use Pb-based alloys that have a melting point of about 507 K. Although restriction of Pb is globally growing, and the practical use of the Pb-free solder has spread, alternative materials are inadequate to replace high temperature Pb-based solder. So, we tried to develop a new joining technology using vacuum evaporation deposition.This study aims to replace Pb-based solder by intermetallic compound (IMC) with vacuum evaporation deposition. To form the IMC that has a high melting point, we used interactions between Ag/Sn/Cu deposited films. The films consisting of Ag, Sn and Cu were prepared by depositing them on Si. Total thickness of the evaporated film was about 5.0 mm. Samples were produced to join the Si chip with the evaporated films to Cu substrate.We confirmed the complete transformation into the IMCs from the evaporated films at 573 K for 30 s. The cross-section of the joining part between Si chip and Cu substrate had two thick layers and one thin layer. They were identified as the following layers by TEM analyses; The upper layer was Cu6Sn5, the middle layer was (Ag,Cu)3Sn based on Ag3Sn, and the lower layer was Cu3Sn. Since their melting points are more than 688 K, they are much higher than heat resistance temperature, 533 K, which is required for high temperature solder. As a result, the joint part showed high strength at high temperature, and the strength at 543 K showed 21.3 MPa, which was a higher value than in use of Pb-based solder. This result proved that the joint part formed by the evaporated films had good heat resistance at high temperature.Moreover, nanoindentation test and modulated thermoreflectance microscopy respectively evaluated mechanical and thermal properties of (Ag,Cu)3Sn and Cu3Sn, including Ag, Cu and Si as reference. Generally, mechanical property of IMC is considered to be hard and brittle. However, the nanoindentation test revealed a large difference between both IMCs. Hardness and elastic modulus of Cu3Sn was much higher than those of (Ag,Cu)3Sn. The elastic modulus of (Ag,Cu)3Sn was also lower than that of Cu, and its hardness was less than half that of Cu3Sn. When the high elastic modulus material forms the joint part, the joint may fracture and the Si chip may crack owing to the thermal stress. Thus, mechanical property of (Ag,Cu)3Sn is expected to relax the stress. Besides, modulated thermoreflectance microscopy revealed (Ag,Cu)3Sn and Cu3Sn has good thermal properties because the thermal properties are better than Pb, Sn. Therefore, thermal energy generated at Si chip is expected to rapidly conduct to the joint part and Cu substrate.
9:00 PM - V4.24
Characterization of Protein Micro-arrays on a Cell Repulsive Film for Cell-surface Interactions.
Ana Ruiz 1 , Laura Ceriotti 1 , Lucel Sirghi 1 , Hubert Rauscher 1 , Ilaria Mannelli 1 , Leonora Buzanska 1 2 , Sandra Coecke 1 , Pascal Colpo 1 , Francois Rossi 1
1 , Joint Research Center, Ispra Italy, 2 Medical Research Clinical Institute, Polish Academy of Sciences, Warsaw Poland
Show AbstractCell based micro-arrays represent a promising alternative to microwell plates for high throughput analysis of cellular functions, such as cell adhesion and differentiation on a large variety of materials. In this work, protein arrays are created on plasma deposited polyethylene oxide (PEO-like) film as non adhesive background by using micro-spotting and microcontact printing . The pattern quality produced by both techniques has been characterized and compared in terms of coverage and bio activity. PEO-like films have been proven to be protein and cell repulsive in solution, but protein adhesive when proteins are deposited either by piezoelectric microspotting or microcontact printing techniques. Microspotting deposition has been implemented due to the possibility of testing many proteins on the same substrate, as well as stacking multiple protein layers. Microcontact printing has been chosen due to the flexibility to produce customized layout configurations and the simplicity of its procedure. By these two methods we have been able to obtain protein patterns with different protein coverage on the PEO-like film, as assessed by Atomic Force Microscopy (AFM) and Ellipsometry. The results show that, after spotting, only a small amount of the fibronectin (model protein used in this study) is retained on the surface and present different layer densities depending on the initial protein solution concentration. On the contrary, microstamped protein patterns exhibit a uniform distribution of densely packed proteins regardless on the initial inking concentration. Both the surface analysis methods confirm a stamped protein layer thickness of 3.5 nm height in dried conditions, which increases to 6 nm after immersing in liquid, as observed by AFM and in agreement with the fibronectin dimensions. Both printed and spotted fibronectin molecules resulted to be strongly immobilized on the surface with the active binding sites available for immunorecognition, as assessed by Surface Plasman Resonance Imaging (SPRi) and cell culture experiments. Such protein patterns have been used to create stem cell arrays providing a platform where different cell developmental processes, such as migration, proliferation and differentiation, can be studied.
9:00 PM - V4.25
Absorption Spectra of Ferroic (NH2(C2H5)2)2CuCl4 Nanocrystals Incorporated into the Photopolymer Matrix.
Kazimierz Plucinski 1 , Volodymyr Kapustianyk 2 , Ivan Kityk 3
1 Electronics Department, Military Univ. of Technology, Warsaw Poland, 2 Scientific Technical and Educational Centre of Low Temperature Studies, Univ. of Lviv, Lviv Ukraine, 3 Faculty of Chemistry, Silesian University of Technology, Gliwice Poland
Show Abstract9:00 PM - V4.3
Remendable Materials Using Reversible Covalent Bonds.
Amy Peterson 1 , Giuseppe Palmese 1
1 Chemical & Biological Engineering, Drexel University, Philadelphia, Pennsylvania, United States
Show AbstractMaterials that can recover mechanical properties following failure offer increased safety and service life. Inspiration for remendable materials comes from nature and has led to many biomimetic mechanisms for healing such as the inclusion of vascular networks that “bleed” healing agent upon crack formation. Two approaches for healing polymer networks have captured much attention. In one method, polymer networks are made to self-heal by adding encapsulations filled with uncured resin, which break open upon crack formation, causing resin to flow into and fill the crack surface. The other mechanism relies on the inherent reversibility of bonds (covalent, noncovalent, or physical) in the polymer network to heal. Our approach to self-healing composites combines many advantages of healing via encapsulation and healing via reversible bonds. Incorporation of a healing agent allows for crack healing while maintaining the desirable physical and mechanical properties of the base thermoset. Reversible bonding of the healing agent provides crack healing multiple times.We report on the development of two healing systems for epoxy-amine thermosets based on the thermoreversible Diels-Alder reaction of furan and maleimide. In one, crack healing of a traditional epoxy-amine thermoset is induced by thermally reversible crosslinking of a secondary phase. In the other, furan functionalization of an epoxy-amine thermoset allows for in situ crack healing of this thermoset with a bismaleimide solution. Both phenomena occur at room temperature and minimal pressure and significant load recovery is possible multiple times in a given location.Load recovery is postulated to be the result of both physical and chemical bonding across the crack surface. Physical bonding is caused by solvent-mediated swelling and subsequent interlocking of crack surfaces, while chemical bonding results from the Diels-Alder reaction of furan and maleimide. This form of the Diels-Alder reaction is reversible, forming a ring structure at room temperature and reforming the respective diene and dienophile between 60 and 90°C.
9:00 PM - V4.4
Experimental Method for Characterizing Force Response in Hydrogels
John Springmann 2 , Wendy Crone 1 2
2 Engineering Mechanics, University of Wisconsin - Madison, Madison, Wisconsin, United States, 1 Engineering Physics, University of Wisconsin - Madison, Madison, Wisconsin, United States
Show AbstractResponsive hydrogels are polymers that undergo volume changes when exposed to stimuli such as temperature, pH, or electric current. Due to their autonomous response, they have been used as components in microfluidic devices. In order to be implemented successfully as a sensor/actuator, the amount of force the hydrogel exerts when it swells must be known. However, a method for accurately characterizing the force response has not yet been demonstrated in the literature. This research seeks to develop a validated method to characterize a range of responsive hydrogel characteristics. In this research, cylindrical posts of UV-polymerizered 2-(dimethylamino)ethyl methacrylate 2-hydroxyethyl methacrylate hydrogels with a diameter of 600 μm and a height of 250 μm are investigated using a displacement-controlled mechanical testing technique. Results show that the force response varies with gel volume and with polymerization intensity of the gel.
9:00 PM - V4.5
Solvomechanical Response of Diazobenzene Polymer Films in Organic Solvents.
Jianxia Zhang 1 2 , John Wiley 1 2
1 Chemistry, University of New Orleans, New Orleans, Louisiana, United States, 2 AMRI, University of New Orleans, New Orleans, Louisiana, United States
Show AbstractDiazobenzene polymer thin films show rapid mechanical response on exposure to select solvent systems. Either on emersion or evaporation of particular organic solvents, films can bend or curl within seconds. The response not only depends on the nature of the solvent but also on film thickness and the geometry of the polymer piece. In this presentation, the various trends in solvomechanical response will be reported and mechanistic implications for this behavior discussed.
9:00 PM - V4.6
Preparation of Asymmetric Thermosensitive Double-layer Gel.
Takashi Iizawa 1 , Akihiro Terao 1
1 Department of Chemical Enginering, Hiroshima University, Higashi-Hiroshima Japan
Show AbstractPoly(N-alkylacrylamide) (PNAA) gels containing C2-C3 alkyl groups have attracted much attention as smart materials because they have lower critical solution temperatures (LCST), depending on the alkyl groups. They are usually prepared by the radical polymerization of the corresponding monomers. Recently, we have reported novel synthesis method of PNAA by direct condensation of poly(acrylic acid) gel-DBU salt (DAA) with an alkylamine using triphenylphosphite (TPP) as an activating agent, and its application to preparation of core-shell type gels containing two different thermosensitive PNAA layers such as poly(N-isopropylacrylamide) gel (PNIPA, LCST: 32°C) and a poly(N-n-propylacrylamide) (PNNPA, LCST: 21°C). To develop thermosensitive gels deformed markedly by the swelling-deswelling, this paper investigates a new approach to the preparation of asymmetric thermosensitive PNIPA-PNNP double-layer gels by several procedures using the synthetic method of the core-shell type gels.When a DAA sample (diameter: 5.3 mm, length: about 20 mm) was placed in N-methyl-2-pyrrolidone containing an excess of alkylamine and TPP, selective amidation occurred from the outside to give the corresponding DAA-PNAA core-shell type gel consisting of an unreacted DAA core and a quantitatively amidated shell layer, and finally afforded a PNAA gel. Further amidation of DAA-PNAA core-shell type gel with other alkylamine resulted a novel core-shell type gel consisting of two different PNAA layers, PNAA(2) and PNAA(1). Thermal properties of the resulting gel such as swelling/deswelling behavior and equilibrium swelling ratio were measured in water at various temperatures. The swelling/deswelling of shell layers and cores in the PNAA(2)-PNAA(1) core-shell type gel occurred almost independently in response to the temperature changes, although the swelling/deswelling rate of the core was affected by the hydrophilic/hydrophobic properties of the shell layer. However, the resulting cylindrical PNAA(2)-PNAA(1) core-shell type gel cannot deform markedly by the swelling-deswelling because of its axial symmetry. In contrast to the cylindrical gels, the semicylindrical PNIPA-PNNPA double-layer gel prepared by cutting the cylinders into halves was bent markedly in water at a temperature between LCSTs of both layers. The deformations among the swelled gel (a temperature below the LCSTs), the bent gel (a temperature between the LCSTs), and the deswollen gel (a temperature above the LCSTs) occurred reversibly in response to the stepwise temperature changes. We also proposed the several procedures of asymmetric thermosensitive PNIPA-PNNPA double-layer gels, such as a thin long asymmetric thermosensitive double-layer gels (diameter: 0,8 mm, length: about 80 mm) bent in zigzag with high-speed responsivity, using the synthetic method of the core-shell type gels.
9:00 PM - V4.7
Formation of Wrinkle Patterns on Porous Elastomeric Membrane and Their Fabrication of Hierarchical Architectures.
Yue Cui 1 , Shu Yang 1
1 Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States
Show Abstract9:00 PM - V4.9
Thin Poly(styrene-block-4-hydroxystyrene) Block Copolymer Films Spin Coated Directly on Topographic Pre-pattern Substrates.
Geuntak Lee 1 , Pil Sung Jo 1 , Bokyung Yoon 1 , Taehee Kim 1 , Himadri Acharya 1 , Ho-Cheol Kim 2 , June Huh 3 , Cheolmin Park 1
1 Materials science and engineering, Yonsei University , Seoul Korea (the Republic of), 2 , IBM Almaden Research Center, San Jose, California, United States, 3 Materials science and engineering, Seoul National University, Seoul Korea (the Republic of)
Show AbstractWe have investigated the formation of as-cast thin films of a poly(styrene-block-4-hydroxystyrene) (PS-b-PHOST) copolymer directly spin coated on topographic pre-pattern substrates. Either wetting or dewetting of a polymer thin film occurs in non-equilibrium state during spin coating process with solvent vapor saturated and strongly depends on the dimensions of the pre-patterns. The ratio of periodic unit area to elevated one of a pre-pattern ( β value) is found as one of the most important factors for wettability of a thin film. The dewetting of a thin film, guided by the edges of both elevated individual periodic lines and mesas, took place with self assembled block copolymer nanostructure when β value was greater than a critical value of approximately 4 which tends to decrease with the trench depth of the pre-patterns in our system.
Symposium Organizers
Ji Su NASA Langley Research Center
Li-Peng (Leo) Wang TricornTech Corporation
Yasubumi Furuya Hirosaki University
Susan Trolier-McKinstry The Pennsylvania State University
Jinsong Leng Harbin Institute of Technology
V5: Novel Active Materials: Polymers
Session Chairs
Tuesday AM, December 02, 2008
Commonwealth (Sheraton)
9:30 AM - **V5.1
An Artificial Muscle Actuated by Metal Hydrides.
Alex Vanderhoff 1 , Kwang Kim 1
1 Mechanical Engineeering, Univ. of Nevada, Reno, Reno, Nevada, United States
Show AbstractA pneumatic artificial muscle has been converted into a smart actuation system powered with hydrogen gas using a metal hydride reactor unit. The actuator contracts when pressurized, creating a pulling force and the design is based on McKibben muscle concepts. The metal hydride material used in the reactor absorbs and releases hydrogen gas upon cooling and heating, respectively, therefore providing the gas to pressurize the actuator. The system is compact, lightweight, noiseless, provides smooth muscle-like actuation, and has a high force to weight ratio. The experiments conducted in this study show that the system has the potential to be used for biorobotic applications in a wide range of temperature environments and that the embedded braided pneumatic muscle is a feasible design for these applications.
10:00 AM - V5.2
Cellulose Electroactive Paper (EAPap): The Potential for a Novel Electronic Material.
Joo-Hyung Kim 1 , Kwangsun Kang 1 , Sungryul Yun 1 , Sangyeul Yang 1 , Min-Hee Lee 1 , Jung-Whan Kim 1 , Jaehwan Kim 1
1 Mechanical Engineering, INHA University, Incheon Korea (the Republic of)
Show Abstract10:15 AM - V5.3
Rheology and Electrorheology of Nanorod-Loaded Liquid Crystalline Polymers.
Ana Cameron-Soto 1 , Sonia Aviles-Barreto 1 , Aldo Acevedo-Rullan 1
1 Department of Chemical Engineering, University of Puerto Rico, Mayaguez, Mayaguez, Puerto Rico, United States
Show AbstractThe effect of carbon nanotube concentration and dispersion on the rheology of liquid crystalline solutions of hydroxypropyl cellulose (HPC) has been experimentally studied. The rheology of nanocomposites of HPC and multiwalled carbon nanotubes (MWCNT) in m-cresol were characterized in steady-state, transient dynamic tests. The rheology as particle loading increases shows a very distinct response in the magnitude and scaling of the steady-state viscosity, and the storage and loss modulus. The liquid crystalline phase was characterized by direct observations by reflected polarized light microscopy. Additionally, an electric-field effect was observed on the rheology of the HPC/MWCNT in m-cresol soft composites. The HPC in m-cresol matrix is non-responsive, thus the electrorheological effect is due to the presence of the carbon nanotubes. The mechanism for this effect is still uncertain, since it does not follow the scaling predicted by simple models for heterogeneous and homogeneous ER fluids.
10:30 AM - V5.4
Mechanics of Soft Active Materials.
Xuanhe Zhao 1 , Wei Hong 1 2 , Zhigang Suo 1
1 School of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts, United States, 2 Department of Aerospace Engineering, Iowa State University, Ames, Iowa, United States
Show AbstractPolymers and polymeric gels are representative of “soft materials” as opposed to “hard materials” (e.g., metals and ceramics). Soft materials can be made active in that they can undergo large deformation in response to diverse stimuli, including mechanical stresses, electric fields, and trace amount of enzymes.Our interest in active soft materials has been stimulated by recent development in the fields of dielectric elastomer actuators and stimuli-responsive gels. In this talk I’ll focus on our new formulation of nonlinear field theory of elastic dielectrics.Two difficulties have long troubled the field theory of finite deformation in dielectric solids. First, when two electric charges are placed inside a dielectric solid, the force between them is not a measurable quantity. Second, when a dielectric solid deforms, the true electric fieldand true electric displacement are not work conjugates. These difficulties are circumvented in our new formulation of the theory. Imagine that each material particle in a dielectric is attached with a weight and a battery, and prescribe a field of virtual displacement and a field of virtual voltage. Associated with the virtual work done by the weights and inertia, define the nominal stress as the conjugate to the gradient of the virtual displacement. Associated with the virtual work done by the batteries, define the nominal electric displacement as the conjugate to the gradient of virtual voltage.Our approach does not start with Newton’s laws of mechanics and Maxwell-Faraday theory of electrostatics, but produces them as consequences. We show that the notion of Maxwellstress, which is widely used in the literature, has no general theoretical basis. However, for a very special class of materials, which we call ideal dielectric elastomers, the theory recovers the Maxwell stress.
10:45 AM - V5.5
Absorption-induced Deformations of Nanofiber Yarns and Nanofibrous Webs.
Daria Monaenkova 1 , Konstantin Kornev 1 , Taras Andrukh 1
1 MSE, Clemson University, Clemson, South Carolina, United States
Show AbstractCurrent advances in manufacturing of nanotubular and nanofibrous materials with high surface- to - volume ratios call for the development of adequate characterization methods and predictive estimates of their absorption capacity. Extremely high flexibility of these materials poses a challenge: their pore structure easily changes upon contact with the fluid in question. One more complication is that the absorption process is sufficiently fast: one hundred micron droplets disappear in milliseconds. This paper sets a physical basis for analyses of absorption processes in nanotubular and nanofibrous materials. As an example, we study absorption of droplets by yarns made of nanofibers and nanofibrous webs. Through our experiments we show that absorption can induce different types of nanoyarn deformations: visible deformations of the yarn profile and deformations of the yarn diameter/length caused by the capillary pressure. Using our experimental data and theory, we estimate elastic and transport characteristics of the nanofibrous materials. The reported experiments and proposed theory open a new area of research on absorption-induced deformations of nanotubular and nanofibrous materials and show their potential applications as sensors to probe minute amount of absorbable liquids.
V6: Novel Active Materials: Composites
Session Chairs
Tuesday PM, December 02, 2008
Commonwealth (Sheraton)
11:30 AM - **V6.1
Recent Progress and Application of Novel Smart Composite Materials.
Shanyi Du 1 , Jinsong Leng 2
1 Centre for composite materials, Harbin Institute of Technology, Harbin China, 2 Centre for composite materials, Harbin Institute of Technology, Harbin China
Show Abstract12:00 PM - V6.2
High Modulus Nanolayer / Elastomer Hybrids for Vibration Damping.
Erik Dunkerley 1 , Hilmar Koerner 2 , Richard Vaia 2 , Daniel Schmidt 1
1 Plastics Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, United States, 2 , Air Force Research Labs, Wright-Patterson AFB, Ohio, United States
Show AbstractEngineered laminates find use in everything from automotive applications to airframes, in large part due to their unique combination of toughness and modulus. Nature also utilizes laminates, nacre being one of the most well-known. Comprised of hexagonal platelets of aragonite 10-20 µm wide and 0.5 µm thick separated by protein-based elastic biopolymers, the mechanical interlocking of the platelets, the immobilized protein within the CaCO3 and “hidden length” of the intervening biopolymer chains give rise to exceptional toughness and damage tolerance. Coupled with the ideas of mechanical contrast and interfacial slip, it may be possible to take lessons from these examples to produce uniquely stiff, robust, highly damping materials from nanoscopic laminates.In this study, hybrids consisting of organically modified montmorillonite (MMT) nanolayers and 0-30 vol% polyisobutylene (PIB) are produced via spray-coating and solvent-casting. Free-standing films result, and in addition to their optical transparency, display a unique combination of stiffness and damping capacity, including simultaneous storage and loss moduli as high as ~7-10 GPa and ~0.7-0.8 GPa respectively, and loss moduli of ~0.3-0.8 GPa over a temperature range of nearly 200 K and four decades of frequency. Small angle x-ray scattering indicates a highly aligned (Sd > 0.75) superstructure parallel to the plane of the film, with the polymer distributed throughout the structure and strongly confined between the nanolayers.Alterations in the preparation technique modify the process of evaporation-induced self-assembly (EISA) by which these materials form, allowing for variations in hierarchical structure and control over the hybrid’s thermomechanical properties. In contrast to bottom-up approaches like layer-by-layer deposition, the methods developed here represent a rapid, readily scalable means of achieving nanoscopic interpenetrating brick-and-motor morphologies, in this case consisting of rigid nanolayers coupled by a soft polymeric phase, and allow for alterations in the mesoscopic organization of these nanostructures that are otherwise difficult to achieve. The combination of large dynamic mechanical losses and structurally relevant moduli provide novel options to suppress vibration in rigid composites.
12:15 PM - V6.3
A Novel Approach for Processing 2 – 2 Single Crystal / Polymer Composites.
Michael Ugorek 1 , Gary Messing 1 , Susan Trolier-McKinstry 1
1 Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State Universtiy, University Park, Pennsylvania, United States
Show AbstractAn understanding of microstructure evolution in ceramic materials, including texture development and abnormal / enhanced grain growth should enable more controlled final microstructures. In this study, a novel approach for fabricating 2-2 single crystal / polymer composites with a kerf of < 5 microns was demonstrated. As a model system, surface templated grain growth was used to propagate a single crystal interface into a polycrystalline BaTiO3 or Ba(Zr0.05Ti0.95)O3 matrix with lamellar metal layers. Grain growth evolution and texture development were studied using both [001] and [110] BaTiO3 single crystal templates. It was found that the growth kinetics can be controlled by a small initial grain size, atmosphere conditions, and the introduction of a liquid phase at selective areas / interfaces. By using a PO2 of 1x10-11 atm during high temperature heat treatment, matrix coarsening was limited while enabling single crystal boundary motion up to 0.3mm during growth between 1250oC and 1300oC. By removing the inner electrodes, a 2-2 single crystal composite can thus be prepared. The piezoelectric and dielectric properties of the composites as a function of composition and single crystal orientation will be reported. This method is expected to be generally useful in preparing single crystal composites of a wide range of compositions.
12:30 PM - V6.4
The Influence of Processing Variables on the Morphology and Performance of a Two-Dimensional Conducting Fiber Reinforced Dielectric Elastomer Composite Material.
Brian Stewart 1 , Kathryn Logan 1
1 Materials Science and Engineering, Virginia Polytechnic Institute, Blacksburg, Virginia, United States
Show AbstractDielectric elastomer (DE) actuators based on elastomeric films have been intensely studied in recent years. Most of this prior work was based on one-dimensional planar actuators with a compliant electrode on either side to generate the necessary electric field. Typical analyses of planar actuators began with the one-dimensional form of the Maxwell stress tensor and assumed a uniform electric field. While this approach resulted in simple geometry and representation of the electric field, the use of the sheet form of the DE material combined with the 1-D field assumption imposed severe limits on possible composite morphologies. There have also been notable attempts to include “inextensible fibers” as reinforcement in the elastomer matrix. These were likewise fabricated from the sheet form of DE, with various attempts to form actuators by rolling, folding or stacking fiber reinforced sheets. Our research departs from prior work by producing an intrinsic two-dimensional fiber-reinforced composite material with electrically conductive reinforcing fibers. This material is produced by processing the uncured liquid precursor form of the elastomer while in direct contact with the fibers. The use of the liquid form allows for a wider array of potential configurations, and permits the inclusion of electrically conductive reinforcing fibers throughout the bulk of the composite. The use of the two-dimensional configuration requires analyses using the two-dimensional formulation of the divergence of the Maxwell stress tensor to compute field-generated body forces and surface tractions. The analysis is further complicated by the coupling of the two-dimensional electrical domain with that of the three-dimensional structural domain. The result is an analysis that includes not only the effects of fiber fraction normally found in passive composite materials, but also the effects of dielectric elastomer physical features such as electrode spacing on performance variables such as actuation voltage. The results to be presented include static finite element analysis (FEA) predictions, actuator performance data, and observations of the effect of processing parameters on both the morphology and performance of the composite material. The numerical results are compared to the measured force and displacement data from tensile actuators fabricated using the new method. The effects of processing variables such as elastomer precursor viscosity and curing environment on fiber spacing and fiber fraction are presented to show how different processing options affect the form and performance of the finished product. The processing observations will be used to guide more detailed materials characterization studies. The combination of numerical and experimental results provides an estimation of the performance envelope of this novel material system.
12:45 PM - V6.5
Ionic Polymer-Metal Composites Processed by Hot Pressing: Effect on Capacitance and Energy Harvesting.
Rashi Tiwari 1 , Sang_Mun Kim 1 , Kwang Kim 1
1 Mechanical Engineeering, Univ. of Nevada, Reno, Reno, Nevada, United States
Show AbstractV7: Optics
Session Chairs
Jinsong Leng
Paul Mulvaney
Paul Muralt
Baoxiang Wang
Tuesday PM, December 02, 2008
Commonwealth (Sheraton)
2:30 PM - V7.1
Nano-optical Negative-index Photonic Crystal Lenses for Subwavelength Imaging and Next-generation Optoelectronics.
Bernard Casse 1 , Wentao Lu 1 , Yongjian Huang 1 , Srinivas Sridhar 1
1 Electronic Materials Research Institute, Northeastern University, Boston, Massachusetts, United States
Show AbstractWe use bandstructure engineering principles to engineer photonic crystal (PhCs) lenses which exhibit an effective negative index of refraction to manipulate light at the nanoscale level for subdiffraction imaging and next-generation optoelectronics applications. The PhC lenses are nanofabricated in an InP/InGaAsP heterostructure semiconductor platform using modern lithography techniques and characterization is performed using near-field scanning optical microscopy. We report the first experimental observation of subwavelength imaging (~0.40λ) in a photonic crystal superlens at optical frequencies (1.5 µm). Then, we experimentally demonstrate that by exploiting the periodicity of the surface corrugation, a binary-staircase optical element can be engineered to exhibit an effective negative index of refraction and focus plane-waves. Finally we demonstrate a superior negative-index 2D PhCs planoconcave microlens having compact footprint, ultra-short focal length (~8λ), diffraction-limited spot size (~0.68λ), larger numerical aperture (close to unity) and reduced spherical aberrations compared to a conventional positive index planoconvex lens.This work was supported by the Air Force Research Laboratories, Hanscom through grant no. FA8718-06-C-0045 and the National Science Foundation through grant no. PHY-0457002.
2:45 PM - V7.2
Characterization of Optical Metamaterials.
Nicholaos Limberopoulos 1 , Alkim Akyurtlu 1 , Aram Karakashian 2 , William Goodhue 2 , Michael Coulombe 2
1 Electrical and Computer Engineering, University of Massachusetts, Lowell, Massachusetts, United States, 2 Physics and Applied Physics, University of Massachusetts, Lowell, Massachusetts, United States
Show AbstractValidation of the unique properties, i.e. negative index of refraction, of optical metamaterials is an important aspect of metamaterial design and applications. In this work, a testbench structure, based on surface-plasmon coupling, for the characterization of optical metamaterials will be demonstrated. The main idea behind this structure is based on the fact that in conventional (positive index materials), surface plasmon coupling only occurs for p-polarization, where it has been shown (R. Ruppin, Journal of Physics: Condensed Matter 13, 1811-1819, 2001, and N. Limberopoulos, G. S. Banks, A. Akyurtlu, A. S. Karakashian, W. D. Goodhue, and V. Limberopoulos, 2007 USNC/URSI National Radio Science Meeting, July 23 2007, Ottawa, ON, Canada.) that for a negative index metamaterial, surface plasmon coupling occurs for both p- and s-polarizations. We take advantage of this property to validate negative index properties of our optical negative index metamaterials (NIMs) (A. G. Kussow, A. Akyurtlu, A. Semichaevsky, N. Angkawisittpan, Physical Review B, 76, 195123, 1-7, 2007). The test bench structure is composed of a BK7 prism coupler and the NIM slab under test. The structure is exposed to free space. This design configuration has been chosen over typical Otto and Kretschmann configurations for its simplicity. The prism coupler is used to couple the light into the NIM under test that is to be characterized. The design parameters of the metamaterial samples, the thicknesses of the layers in the test bench structure, as well as the details of the coupling mechanisms are determined by the Finite Difference Time Domain (FDTD) method. Results of the theoretical and computational models will be validated through experimental results of the fabricated structures.
3:15 PM - **V7.4
Mapping the Surface Plasmon Resonance Landscape of Gold Nanocrystals.
Paul Mulvaney 1
1 School of Chemistry & Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
Show Abstract3:45 PM - V7.5
Supercontinuum Generation in Toroidal Chalcogenide Microresonators.
Duygu Akbulut 1 , Abdullah Tulek 1 , Mehmet Bayindir 1 2
1 UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara Turkey, 2 Department of Physics, Bilkent University, Ankara Turkey
Show AbstractWhispering gallery mode microresonators confine light to a micron scale volume via total internal reflection mechanism. Among many different types of such structures, microtoroids have attracted much attention since their first demonstration due to the possessed features of ultra-high quality factor, small mode volume and integrability to chip based applications. Until now, such structures have been employed for a variety of purposes including sensor applications, observation of nonlinear optical effects and laser action. Chalcogenide glasses are materials that maintain considerably high nonlinear refractive index compared to other glasses; hence they have drawn much attention in nonlinear optics applications such as supercontinuum generation and parametric processes. In this work, we propose to combine the small mode volume and ultrahigh quality factor of the toroidal microcavity with high nonlinearity of the chalcogenide materials to obtain a strong nonlinear optical effect and to observe generation of new frequency components inside the microresonator which would result in a chip-integrable device that could be used for optical frequency metrology, spectroscopy, tunable parametric amplification and pulse compression purposes. For this purpose, toroidal microresonators are fabricated from SiO2 material via conventional lithography and etching techniques combined with a laser reflow procedure. The obtained SiO2 microtoroid is used merely as a template which is to be modified for intended applications and a chalcogenide material with nonlinear refractive index ~1000 times higher than that of silica is thermally evaporated on top for observing supercontinuum generation in the toroidal microresonator. 2D finite difference time domain (FDTD) simulations have been performed for the chalcogenide coated SiO2 microtoroids. The simulation results revealed that the cavity modes are mostly confined in the nonlinear material layer due to high refractive index contrast at the chalcogenide-air and chalcogenide-silica interfaces and new frequency components in the cavity due to nonlinear processes of self phase modulation are indeed observed.
4:30 PM - V7.6
An Approach to Develop an Integrated Process for the Development of Smart Luminescent Sensor Materials for Structural Health Monitoring Systems: The Case Study of BAS:Eu Triboluminescent Ceramics.
Kaustav Sinha 1 , Brett Pearson 1 , Said Casolco 2 , Javier Garay 2 , Olivia Graeve 3 1 , Brandon Williams 1
1 Chemical and Metallurgical Engineering, University of Nevada, Reno, Reno, Nevada, United States, 2 Mechanical Engineering, University of California Riverside, Riverside, California, United States, 3 Kazuo Inamori School of Engineering, Alfred University, Alfred, New York, United States
Show Abstract4:45 PM - V7.7
Optical Characterization of GaN Nanorods by Spectroscopic Ellipsometry.
Shih-Hsin Hsu 1 , Ching-Hua Chiu 2 , Hao-Chung Kao 2 , Tien-Chang Lu 2 , Shing-Chung Wang 2 , Yuh-Jen Cheng 1 , Yia-Chung Chang 1 2
1 Research Center for Applied Sciences, Academia Sinica, Taipei Taiwan, 2 Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu Taiwan
Show AbstractGaN nanorods demonstrating broad angular and spectral antireflection are characterized by spectroscopic ellipsometry (SE). The undoped GaN samples were first epitaxially grown by metal organic chemical vapor deposition on c-plane sapphire (0001) substrates. Thin Ni films with various thicknesses ranging from 5 to 20 nm were subsequently evaporated, and followed by a rapid thermal annealing process under N2 gas to form Ni nano-dots of different sizes, which served as the etching masks. After being etched by an inductively coupled plasma reactive ion etching process till the heights of GaN rods were over 700 nm, the samples were dipped into a heated nitric acid to remove the residual Ni nano-masks. The fabricated samples consist of a layer of irregular GaN nanorods with various in-plane sizes (from below 50 to 400 nm) and shapes and a homogeneous GaN film on a sapphire substrate, and the total thicknesses of the GaN layers are all around 2 μm. Optical reflection measurements show the reflectance for both p- and s-polarizations is held well below 10 percent from ultraviolet to infrared wavelengths and at incident angles up to 60 degree.Variable-angle spectroscopic ellipsometry measurements of the GaN nanorods were carried out in a spectral range from ultraviolet to infrared (300 to 2200 nm in wavelength) using a rotating analyzer ellipsometer system with an adjustable retarder, which is capable of measurements of depolarization degree and generalized ellipsometry. Effective medium approximation (EMA) theory was employed to analyze this kind of porous nanostructure. Within the analysis, the GaN nanorods were modeled as a graded-index layer, in which each sub-layer is modeled as a mixture of GaN, whose uniaxial optical constants were obtained from SE studies on homogeneous planar GaN films, and voids with varying porosity fraction. In addition to material anisotropy, the columnar structure of nanorods also introduces anisotropy, which was modeled by adjusting the depolarization factor to describe the directional dependence of the EMA screening effect. The model fitting based on a 3-node, graded EMA layer model works pretty well in the infrared region, where the feature sizes of the nanorods are relatively small compared with probe wavelengths. For the samples with smaller rod sizes, the model could fit the experimental data down to visible wavelengths. It is worth noting that the refractive index profiles of GaN nanorods extracted from the analysis also verify the broad spectral and angular antireflection is mainly attributed to the gradually varying porous structure. [1] This study demonstrates that SE measurements coupled with an adequate modeling could be a useful, nondestructive tool for the characterization of structures in micro to nano scale.[1] C.-H. Chiu, P. Yu, H.-C. Kuo, C.-C. Chen, T.-C. Lu, S.-C. Wang, S.-H. Hsu, Y.-J. Cheng, and Y.-C. Chang, Opt. Express 16, 8748 (2008).
5:00 PM - V7.8
Pb(Zr,Ti)O3 Nanofibers Produced by Electrospinning Process.
Ebru Mensur Alkoy 1 , Canan Dagdeviren 1 , Melih Papila 1
1 Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul Turkey
Show Abstract5:15 PM - V7.9
Light-powered Electrical Switch Based on Cargo Lifting Azobenzene Monolayers: the Role of Cooperativity in Molecular Motors.
Paolo Samori 1 2 , Giuseppina Pace 1 , Jeffrey Mativetsky 1 , Mark Elbing 4 , Michael Zharnikov 5 , Marcel Mayor 6 4 , Maria Anita Rampi 3
1 Institut de Science et d'Ingénierie Supramoléculaires, Université Louis Pasteur de Strasbourg, Strasbourg France, 2 Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, Bologna Italy, 4 Institute for Nanotechnology, Forschungszentrum Karlsruhe , Karlsruhe Germany, 5 Angewandte Physikalische Chemie, Universität Heidelberg, Heidelberg Germany, 6 Department of Chemistry, University of Basel, Basel Switzerland, 3 Department of Chemistry, University of Ferrara, Ferrara Italy
Show AbstractNature exploit to a great extent light as a source of energy for operating biological systems. Within photochromes which can convert photonic energy into mechanical energy, azobenzenes have been extensively studied for their unique photoisomerization, potentially enabling switching properties in molecular devices. This is the first study carried on fully conjugated and rigid azobenzene derivatives exhibiting reversible trans-cis photo-isomerization when organized in single-component SAMs (Self-Assembled Monolayer) on Au(111). High-resolution STM images showed that the AZO molecules, both in trans and cis configuration, adopt a rectangular unit cell. Interestingly, we found that the light-induced isomerization is extended over many adjacent molecules arranged into 2D crystalline domains. The long range order found for the cis-domains can be explained in terms of a cooperative nature of the process[1]. The stabilization of the intermolecular interactions among adjacent molecule in the SAM is responsible for the considerably increased yield of isomerization on the surface with respect to solution. Such an azobenzene SAM has been successfully used to modulate the current through metal-organic-metal junctions. By incorporating the azobenzene SAM between a Au(111) support and a metal coated AFM tip, we could detect a 30-fold difference in the current through the junction, providing the first example of conducting AFM measurement on a bi-stable system. [2]Given the occurrence of the isomerization on many thousands adjacent molecules, i.e. on the several hundreds of micrometers scale, we employed a macroscopic mercury drop as counter-electrode and found a reversible change of 1.5 orders of magnitude in the current. Significantly, the cooperative and high yield of switching of many adjacent molecules, chemisorbed on Au was also employed to generate forces acting simultaneously against gravitational effects, atmospheric pressure, and surface tension on a heavy Hg drop. The joint effort of 1011 adjacent molecules, each of them exerting a force of at least 2.6x10 14 N, led to the generation of an overall force per unit area as high as 1x105 N/m2. This unambiguously demonstrates that our azobenzene SAM represents a prototype of a molecular machine able to transport mass, and in particular to act as a cargo lifter.Noteworthy, our cis-trans photoisomerization is fully reversible. In principle it might be used to gate optical signals, and therefore has potential for implementing logic operations on arrays of switching elements, and ultimately for high density data storage based on artificial molecular systems.[1] G. Pace, V. Ferri, C. Grave, M. Elbing, C. von Hänisch, M. Zharnikov, M. Mayor, M. A. Rampi, and P. Samorì, PNAS 2007,104,9937[2] J. Mativetsky, G. Pace, M. Elbing, M.A. Rampi, M. Mayor, P. Samorì, J. Am. Chem. Soc. 2008 in press[3] V. Ferri, M. Elbing, G. Pace, M. Zharnikov, P. Samorì, M. Mayor, M.A. Rampi, Angew. Chem. Int. Ed. 2008,47,3407
5:30 PM - V7.10
Study on the Effect of Temperature on Optical Properties of ZnO Thin Film Using SPR.
Shibu Saha 1 , K. Sreenivas 1 , Vinay Gupta 1
1 Department of Physics & Astrophysics, University of Delhi, Delhi, Delhi, India
Show AbstractZinc Oxide (ZnO) is an important multifunctional material having good electro-optic, photoconducting, piezoelectric, elasto-optic and optical wave guiding properties with wide range of applications. Recently it has attracted a lot of interest towards UV-Lasers due to excellent optical properties and tunable band-gap. The properties of the material are known to depend upon the temperature and may affect the device performance. However, no report is available on temperature dependent optical properties of ZnO thin film. In the present study the optical properties of a RF-sputtered ZnO thin film has been investigated using a simple Surface Plasmon Resonance (SPR) setup based on Kretschmann-Reather configuration. The dip in reflectance for gold-air interface is observed at an angle of 36.8°. The experimentally obtained SPR reflectance curve is fitted with the theoretical curve generated using the Fresnel's equation and dielectric constant of the gold film as the fitting parameter. Hence the dielectric constant of the gold film is obatined. On deposition of ZnO layer on the gold film the SPR dip angle is observed at 46.0°. The dielectric constant of the ZnO film at optical frequency corresponding to 633 nm wavelength is obtained by fitting the experimental SPR reflectance curve with the theoretical curve generated using Fresnel's equation. The SPR reflectance curve of this system (Prism/Au/ZnO) is obtained at different temperatures from 27°C to 250°C. Hence, the dielectric constant and refractive index of the ZnO thin film at different temperatures are obtained. The refractive index of the ZnO thin film is found to increase linearly from 1.95 to 1.98 with increase in ambient temperature, from 27°C (room temperature) to 250°C. Further calculations shows that the bandgap decreases from 3.32eV to 2.91eV with increase in temperature in the same range.The observed linear increase in the refractive index with temperature shows the promising application of ZnO film as an effective temperature sensor.
5:45 PM - V7.11
Optical Fiber Loop Sensors for Structural Health Monitoring of Composites.
Nikhil Gupta 1 , Nguyen Nguyen 1
1 Mechanical and Aerospace Engineering, Polytechnic University, Brooklyn, New York, United States
Show AbstractA variety of intrinsic and extrinsic fiber-optic sensors are used in structural health monitoring of composite materials, including Bragg grating, Fabry-Perot, and interferometric sensors. Most of these sensors are relatively expensive and require elaborate instrumentation for data acquisition and interpretation of results. In the present work an optical-fiber loop sensor is designed and tested for possible applications in structural health monitoring in composite materials. The sensor design and principle are simpler than other optical fiber-based sensors. It is known that bending an optical fiber beyond a critical curvature leads to loss of intensity through the curved region. The intensity loss depends on the radius of curvature. The transmitted light intensity can be measured by a photodetector and a change in the intensity due a change to the curvature can be measured. In the present research optical fiber based loop sensors are developed that can exploit this concept. Single mode optical fiber sensors having different loop radius, from 5-20 mm, are fabricated and calibrated for applied strain on the loop. The calibration is carried out using a 9.8 N load cell and a computer controlled translation stage having 50 nm step resolution. Results show that the sensors provide highly repeatable results for several loading cycles. Smaller loop radius leads to higher intensity losses, resulting in higher sensitivity for the same applied displacement. A theoretical framework is developed for validation of the calibration results and the theoretical results of intensity loss show close agreement with the experimental data. In the next step the loop sensors are embedded in glass fiber/epoxy resin laminates. Two types of laminates, having fibers in 0-90 and ±45 degrees orientation, are used in the study. Result show that the sensors results are consistent with the calibration data and such sensors can be used in structural health monitoring applications. In this approach the coating and cladding of optical fibers are maintained intact; therefore, the sensors are robust and can withstand the fabrication process of various types of composites. These sensors can also be used for temperature measurements.
Symposium Organizers
Ji Su NASA Langley Research Center
Li-Peng (Leo) Wang TricornTech Corporation
Yasubumi Furuya Hirosaki University
Susan Trolier-McKinstry The Pennsylvania State University
Jinsong Leng Harbin Institute of Technology
V8: Actuators and Energy Conversion
Session Chairs
Darrell Schlom
Li-Peng Wang
Wednesday AM, December 03, 2008
Commonwealth (Sheraton)
9:15 AM - **V8.1
Durable Dielectric Elastomer Actuators via Self-Clearable Single Walled Carbon Nanotubes.
Qibing Pei 1 , Wei Yuan 1
1 Materials Science and Engineering, UCLA, Los Angeles, California, United States
Show AbstractDielectric elastomers have been shown to exhibit greater than 200% strain with actuation energy density greatly exceeding those of most existing actuators and muscles. Limited lifetime and manufacturability have hindered the commercialization of these otherwise remarkable polymer actuators. We have introduced fault-tolerance as a new feature for high production yield and actuation stability. The use of single wall carbon nanotube electrodes allows the dielectric elastomers to self-heal. During localized dielectric breakdown at a defect that is intentionally introduced, inherent in the films, or newly formed due to fatigue or stress relaxation, the SWNT electrodes self-clear to isolate the defect from the rest of the active area which can then actuate normally. Fault-tolerance significantly enhances the actuation lifetime during constant voltage and cyclic actuations. It also eliminates a major safety concern for the high voltage actuators.
9:45 AM - V8.2
A Hybrid Actuation System Concept and Applications in the Development of High Performance Electromechanical Devices.
Ji Su 1 , Tian-Bing Xu 2 , Xiaoning Jiang 3
1 , NASA langley Research Center, Hampton, Virginia, United States, 2 , National Institute of Aerospace, Hampton, Virginia, United States, 3 , TRS Technologies Inc., State College, Pennsylvania, United States
Show AbstractA hybrid actuation system (HYBAS) was developed at NASA Langley Research Center. The HYBAS demonstrated significant enhancement in the electrical field inducted displacement. The HYBAS did not only show a high performance electromechanical device, but also provided a concept that utilizes advantages of a combination of electromechanical responses of two constituent materials. The constituent materials can be electroative polymers (EAP), piezoelectric ceramics or single crystals. The consistence between the theoretical modeling and experimental validations make the design concept be an effective route for the developments of high performance actuating devices for many applications. In recent research, the concept has been deployed in and extended to the development of several new electromechanical devices, including 1) high performance piezoelectric triple hybrid actuation system (TriHYBAS), 2) hybrid piezoelectric energy harvesting transduction system (HYBET), 3) advanced electroactive single crystal and polymer actuators for cryogenic actuations, 4) advanced high performance vertical hybrid electroactive synthetic jet actuator (ASJA-V), and 5) advanced high performance horizontal piezoelectric hybrid synthetic jet actuator (ASJA-H). In this presentation, a review of the applications of the HYBAS concept in the device design and the mechanism of the enhancement in the performance of the electromechanical devices will be discussed. In addition, a guideline for the further development of electromechanical devices using the HYBAS concept and related mechanisms will be presented.
10:00 AM - V8.3
Piezoelectric Composites: Electromechanical Properties and Design Maps.
Ronit Kar-Gupta 1 , T. Venkatesh 1
1 Materials Science and Engineering, Stony Brook University, Stony Brook, New York, United States
Show AbstractMonolithic piezoelectric materials have been well-recognized for their unique transduction capabilities and are being considered for a wide variety of applications. Furthermore, the composites’ approach towards mitigating some of the limitations of monolithic piezoelectric materials and enhancing their functional properties has been actively considered as well. Several models have been developed to study the effective properties of select classes of piezoelectric composite materials which enables the comparison of the fundamental properties and the performance characteristics across those particular classes of composites. However, a comprehensive study that provides a quantitative comparison of the fundamental properties and the performance characteristics of all the principal composite classes (where in the constituents exhibit zero-, one-, two- or three- dimensional spatial connectivity) is not yet available. In the present study a three-dimensional finite element model is developed to fully capture the complete electromechanical response of five types of piezoelectric composites (i.e., particulate, short-fiber, long-fiber, laminate, and networked composites) where in the constituent phases could, in general, be elastically anisotropic and piezoelectrically active. It is demonstrated that the geometric connectivity of constituent phases in a composite has a significant influence on the fundamental electromechanical properties and the performance characteristics of a piezoelectric composite. By constructing piezoelectric composite materials design maps, the long-fiber composites (with their highest piezoelectric coupling constants) and interpenetrating networked composites (with their highest piezoelectric charge coefficients) are, respectively, identified are being most suitable for ultrasonic imaging and hydrophone applications. Furthermore, grain-size modifications of the constituent phases can significantly enhance the effective piezoelectric properties of a composite such as coupling constants and charge coefficients of a composite while maintaining suitable acoustic impedance, esp., in the case of the networked composites.
10:15 AM - V8.4
6 Watt Segmented Power Generator Modules using Bi2Te3 and ErAs:(InGaAs)1-x(InAlAs)x Elements Embedded with ErAs Nanoparticles.
Gehong Zeng 1 , Hong Lu 2 , Je-Hyeong Bahk 1 , Ashok Ramu 1 , Arthur Gossard 2 , John Bowers 1
1 Department of Electrical and Computer Engineering, University of California, Santa Barbara, California, United States, 2 Materials Department, University of California, Santa Barbara, California, United States
Show AbstractWe report the fabrication and characterization of segmented element power generator modules of 254 thermoelectric elements consisting of 300 μm Bi2Te3 and 60 μm ErAs:(InGaAs)1-x(InAlAs)x. Erbium arsenide metallic nanoparticles are incorporated to create scattering centers for middle and long wavelength phonons, provide charge carriers, and form local potential barriers for electron filtering. The thermoelectric properties of ErAs:(InGaAs)1-x(InAlAs)x were characterized by variable temperature measurements of thermal conductivity, electrical conductivity and Seebeck coefficient from 300 K to 600 K. Generator modules of Bi2Te3 and ErAs:(InGaAs)1-x(InAlAs)x segmented elements were fabricated and an output power over 6 W was measured. Device modeling shows that the performance of thermoelectric generator modules can further be enhanced by the improvement of the thermoelectric properties of the element materials, and reducing the electrical and thermal parasitic losses.
10:30 AM - V8.5
Quantitative Probing of Electro-mechanical Energy Conversion and Dissipation on the Nanoscale: Band Excitation Piezoresponse Force Microscopy.
Maxim Nikiforov 1 , Stephen Jesse 1 , Roger Proksch 2 , Sergei Kalinin 1
1 , Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States, 2 , Asylum Research, Santa Barbara, California, United States
Show AbstractApplication of ferroelectric and piezoelectric materials as functional components of micro-electromechanical and energy harvesting systems necessitates the probing of efficiency of electromechanical energy conversion processes and dissipation on the nanoscale. In the last decade, piezoresponse force microscopy has emerged as a primary technique for domain visualization and manipulation in ferroelectrics based on detection of local electromechanical response. However, quantitativeness of PFM has traditionally been limited by the strong frequency dispersion of the cantilever and electronic transfer functions that act as mechanical amplifier of surface oscillations. similarly, dissipation in electromechanical process has been inaccessible. In this presentation, we develop a quantitative approach for electromechanical characterization based on band-excitation PFM (BE PFM). In BE-PFM the electrical signal, containing a continuous range of frequencies within a band of choice, excites mechanical oscillation in the sample. When frequency of the electrical signal is close to resonant frequency of the tip – surface junction resonant amplification of the mechanical oscillations occurs. Broad band detection of those oscillations allows us to measure all parameters of those oscillations, such as amplitude, resonant frequency, quality factor and phase shift, independently. The BE PFM was illustrated on rigid ferroelectric materials, such as perovskite oxides, in which extrinsic dissipation during imaging an intrinsic during polarization switching was observed. Finally, in ferroelectric copolymers independent mapping of dissipation, electromechanical response, and local elasticity is demonstrated.Research supported by the Center for Nanoscale Materials Sciences, Basic Energy Sciences, U.S. Department of Energy at Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC.
V9: Thin Film Ferroelectrics
Session Chairs
Koukou Suu
Susan Trolier-McKinstry
Wednesday PM, December 03, 2008
Commonwealth (Sheraton)
11:15 AM - **V9.1
Piezo-Ferroelectric Thin Films: From Nucleation to Performance.
Paul Muralt 1
1 , EPFL, Lausanne Switzerland
Show AbstractThe field of piezoelectric thin film microsystems combines an exciting richness of potential applications with many attractive scientific topics on materials processing and physical properties. For real applications, one cannot compromise on materials performance, meaning that integration tasks must be well accomplished to obtain a dense, phase pure material with controlled texture, and a suitable film thickness. Concerning performance for piezoelectric applications, PZT is still the most advanced material for ferroelectric thin films. Remains the question whether further improvement is still possible. There are indeed no simple data and theories available that would instruct us where the limit is, as in the case of non-ferroelectric piezoelectrics for which the knowledge of single crystal properties gives all the answers. Reasons for this complication are domain contributions in combination with the clamping to elastic structures, and deviations from ideal microstructure and interfaces. For full assessment, nano-scale as well as micro-scale properties are of importance. The goal of this talk is to report and comment on current state of the art in processing, properties and understanding, and to give and outlook on prospects for further improvement.
11:45 AM - V9.2
Erbium Alloyed Aluminum Nitride Films For Piezoelectric Applications.
A. Kabulski 1 , V. Pagan 1 , D. Korakakis 1
1 Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, West Virginia, United States
Show Abstract12:00 PM - V9.3
Fabrication of Multiferroic Nano-Composite Films for Micro Biosensor.
Shanthy Sundaram 1 , Sushil Singh 2 , Hiroshi Ishiwara 3
1 Centre for Biotechnology, Allahabad University, Allahabad, U.P., India, 2 Si-MEMS Division, Solid State Physics Lab., Delhi, Delhi, India, 3 Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama, Kento, Japan
Show Abstract12:15 PM - V9.4
Estimation of Piezoelectric PZT Thin Film Coefficients.
Mahmoud Al Ahmad 1 , Erika Fuentes 2 , Leo Baldenegro 2 , Manuel Quevedo-Lopez 2 , Husam Alshareef 2 , Bruce Gnade 2 , Robert Plana 1
1 , LAAS CNRS, Toulouse France, 2 , University of Dallas, Dallas, Texas, United States
Show Abstract12:30 PM - **V9.5
Epitaxial Integration of Smart Materials with Mainstream Semiconductors.
Darrell Schlom 1 , Jon Ihlefeld 1 , Maitri Warusawithana 1 , Ross Ulbricht 1 , Tassilo Heeg 1 , Wei Tian 1 , Seung-Yeul Yang 2 , Qian Zhan 2 , Ying-Hao Chu 2 , Ramamoorthy Ramesh 2 , Cheng Cen 3 , Jeremy Levy 3 , Lena Fitting Kourkoutis 4 , David Muller 4 , Yulan Li 5 , Long-Qing Chen 5 , Joseph Woicik 6 , Jeffrey Klug 7 , Michael Bedzyk 7 , Hao Li 8 , Li-Peng Wang 9 , Yves Idzerda 10 , Jürgen Schubert 11 , Andreas Schmehl 12 , Jochen Mannhart 12
1 Materials Science and Engineering, Cornell University, Ithaca, New York, United States, 2 Department of Materials Science and Engineering, University of California, Berkeley, California, United States, 3 Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 4 Department of Applied and Engineering Physics, Cornell University, Ithaca, New York, United States, 5 Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania, United States, 6 , National Institute of Standards and Technology, Gaithersburg, Maryland, United States, 7 Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States, 8 Physical and Digital Realization Research, Motorola Inc., Tempe, Arizona, United States, 9 , Intel Corporation, Santa Clara, California, United States, 10 Department of Physics, Montana State University, Bozeman, Montana, United States, 11 Institute for Bio- and Nano-Systems (IBN1-IT), Research Centre Jülich, Jülich Germany, 12 Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg Germany
Show AbstractV10/C8: Joint Session: Device Applications of Multiferroics
Session Chairs
Ji Su
Susan Trolier-McKinstry
Wednesday PM, December 03, 2008
Room 210 (Hynes)
2:30 PM - **V10.1/C8.1
Ferroelectric Random Access Memory as a Non-volatile RAM in Multimedia Storage System.
Kinam Kim 1 , Dong Jin Jung 1
1 Memory business division, Samsung Electronics Co. LTD., Yongin-City, Gyunggi-Do, Korea (the Republic of)
Show AbstractThanks to the bi-stable state of ferroelectrics at near ambient temperature, ferroelectric memory has two important characteristics worth mentioning from the operational point of view. First, since core circuitry for the memory does not require stand-by power during quiescent state and the information remains unchanged even with no power supplied, it is thus non-volatile. Second, as the core needs to return the original state after being read, it is called a destructive read-out device. This is because the original information is destroyed after READ. As a consequence, it is essential to return the information back to its original state. This operation is so inevitable in the destructive read-out memory that ferroelectric cell capacitors cannot help suffering frequently from repeated polarization reversals. In particular, when the ferroelectric memory are used as one of the storage devices in computing system, such as byte-addressable memory, the memory has to ensure lifetime memory endurance, which is regarded as the number of READ/WRITE cycles that memory can withstand before loss of any of entire bit information.In the mean time, over the past decades, there has been enormous improvement in VLSI technology to implement system performance of computing platform in many ways. For instance, data throughput of CPU has been increased by thousand times faster than that emerged in the beginning of 1980s. By contrast, state-of-the-art HDD transfers data at 600 MB/sec. Note that data rate of the latest HDD is still orders of magnitude slower than those of the processor/system-memory. To achieve the throughput performance in more effective way, it is therefore needed to bridge performance gap in between each component. On one hand, to compensate the gap between CPU and system memory, CPU cache has been required and adopted. On the other, various technologies have been taken into account to bridge the gap between the system memory and the HDD. In this paper, authors are trying to attempt not only how FRAM provides multimedia storage system such as SSD with performance benefits but also what should be satisfied in terms of reliability in doing so.We demonstrate that FRAM is very eligible to become a non-volatile cache solution, providing benefits both of performance and of reliability. In performance, FRAM cache allows us to rid overhead of power-off recovery in flash translation layer: random WRITE performance has been improved by 250%. Utilizing FRAM as NV-RAM cache could also eliminate FLUSH, which is essential to ensure data integrity in a conventional type. In reliability, in order for FRAM to become NV-RAM cache in such system, what should be overcome is assertion of endurance cycles of 1e15. In line with this, we present what integration technology plays a critical role in achieving 1e15, which is scrutinized systematically and probed by statistical approaches applied to fatigue-data analysis in the latest FRAM.
3:00 PM - **V10.2/C8.2
Development of Mass Production System and Process for Ferroelectric Films.
Koukou Suu 1 , Takehito Jimbo 1
1 Institute for Semiconductor Technologies, ULVAC, Inc., Susono, Shizuoka, Japan
Show AbstractAs for ferroelectric, pyroelectric-sensor etc. that use the bulk material have been used from of old as the functionality device. Recently, the range of use such as ferroelectric random access nonvolatile memories (FeRAM), piezoelectric inkjet printers, the blurring prevention sensors of camera, has extended greatly by developing the ferroelectric thin film. Especially, the miniaturization of all devices is expected from the low power consumption operation, and various developments are advanced. The most typical material is Pb(Zr, Ti)O2 (PZT), but the control of composition and crystalline of PZT thin films were very difficult so far. Moreover, it greatly influences the process, the back and forth such as upper and lower electrodes and the barrier films. We first developed the mass production for FeRAM with the PZT thin film by RF magnetron sputtering, and succeeded in the achievement of uniformity in the wafer, reproducibility and reliability of PZT thin films. Afterwards, the high temperature etching and the MOCVD technology had been developed as next generation FeRAM mass production. Moreover, piezo-electric MEMS mass production technology development has been done at the same time by applying the technology of the mass production sputter tool of FeRAM. In this study, we introduce these ferroelectric device mass production device and processing technology development.
3:30 PM - **V10.3/C8.3
Magnetoelectric Effects in Micro/nanofabricated all Thin Film FeGa/piezoelectric Multilayer Structures.
Ichiro Takeuchi 1
1 Materials Science and Engineering, University of Maryland, College Park, Maryland, United States
Show AbstractWe have fabricated various magnetoelectric (ME) ultilayer structures based on magnetron sputtered FeGa films. The films sputtered onto room temperature Si/SiO2 substrates are polycrystalline as determined by TEM and microdiffraction with a typical grain size on the order of 10s of nm. Magnetostriction of various composition Fe1-xGax films were measured using the cantilever technique, and the lambda100 values extracted are 150~180 ppm for 0.2
4:30 PM - **V10.4/C8.4
PZT based Ferroelectric Materials for Next Generation Mass-Production FRAM.
Takashi Eshita 1 , Wensheng Wang 1 , Osamu Matsuura 1 , Hideki Yamawaki 1 , Satoru Mihara 1 , Yoshihiro Sugiyama 2
1 FRAM Process Engineering, Fujitsu Microelectronics Limited, Kuwana Japan, 2 Embedded Memories Department, Fujitsu Laboratories Limited, Atsugi Japan
Show Abstract5:00 PM - **V10.5/C8.5
Media Material Challenges for Probe based Memory Device.
Qing Ma 1 , Quan Tran 1 , Nathan Franklin 1 , Valluri Rao 1
1 Components Research, Intel, Santa Clara, California, United States
Show Abstract5:30 PM - **V10.6/C8.6
8Mb 1T-1C Ferroelectric Memory Array Embedded within a 130nm Logic Process.
K. Udayakumar 1 , T. Moise 1 , S. Summerfelt 1 , J. Rodriguez 1 , K. Remack 1 , H. McAdams 1 , S. Madan 1
1 Analog Technology Development, Texas Instruments Inc., Dallas, Texas, United States
Show AbstractV11: Poster Session II
Session Chairs
Susan Trolier-McKinstry
Li-Peng Wang
Thursday AM, December 04, 2008
Exhibition Hall D (Hynes)
9:00 PM - V11.1
Finite Element Analysis of Aluminum Nitride Bimorph Actuators – The Influence of Contact Geometry and Position.
V. Pagan 1 , D. Korakakis 1
1 Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, West Virginia, United States
Show AbstractPiezoelectric beams are commonly used in microelectromechanical systems (MEMS) and also have many possible applications in smart sensor and actuator systems. For example, they have been used as the active element in microfluidic and microactuator MEMS devices. In the actuator mode, they employ the converse piezoelectric effect to couple electrical energy into mechanical deformation. Aluminum Nitride (AlN) based devices have attracted much interest because AlN is a piezoelectric material with high thermal stability, high dielectric strength, a reasonable electromechanical coupling coefficient, and a perfect compatibility with standard silicon processing techniques. In this work, the results of 3-dimensional finite element analysis (FEA) of Aluminum Nitride (AlN) homogeneous bimorphs (d31 mode) are shown. The coupled-field FEA simulations were performed using the commercially available software tool ANSYS. The effect of altering the contact geometry and position on the displacement, electric field, stress, and strain distributions for the static case is reported. The geometry and position of the contacts are design parameters that have not been addressed much in the literature. Q. Q. Zhang et al. reported on the fabrication and simulation of d33 cantilever actuators that used interdigitated (IDT) contacts to produce electric fields in the plane of the piezoelectric layer1 while O. J. Aldraihem et al. derived analytical solutions for cantilever beams with piezoelectric patches2. However, generally it is assumed that the top and bottom contacts span the entire length and width of the bimorph. This undoubtedly produces the highest tip displacement in d31 mode bimorphs and leads to the simplest analytical solutions. Nonetheless, the displacement distribution produced is approximately parabolic, and as such, may not be optimal for certain applications. Therefore, the results of 3-d FEA are reported to show that the contact geometry and contact position can be engineered to provide a more ideal response for particular MEMS/smart sensor or actuator systems.1Q. Q. Zhang, S. J. Gross, S. Tadigadapa, T. N. Jackson, F. T. Djuth, S. Trolier-McKinstry, "Lead zirconate titanate films for d33 mode cantilever actuators," Sensors and Actuators A, 105, pp. 91-97, 2003. 2O. J. Aldraihem and A. A. Khdeir, "Precise deflection analysis of beams with piezoelectric patches," Composite Structures, 60, pp. 135-143, 2003.
9:00 PM - V11.10
Tilt Transitions in Ag(TaxNb1-x)O3 Thin Films.
Raegan Johnson 1 , M. Telli 1 , D. Tinberg 1 , S. Trolier-McKinstry 1 , Y. Han 2 , I. Reaney 2
1 Material Science and Engineering, Pennsylvania State University, University Park, Pennsylvania, United States, 2 Department of Engineering Materials, University of Sheffield, Sheffield United Kingdom
Show AbstractPhase transitions involving the tilting of the oxygen octahedra are common in perovskite structures. When the A-site atom is too small for the interstice, the oxygen octahedra will tilt to decrease the volume of the A-site, resulting in improved structural stability of the cell. It is anticipated that the in-plane strains in epitaxial thin films may influence the relative stability of the tilted phases. In this work, epitaxial films of Ag(TaxNb1-x)O3 on LaAlO3 and SrTiO3 substrates were studied due to the rich tilt transition sequence shown in these materials. Ag(TaxNb1-x)O3 films were grown by chemical solution deposition. The solution was spun on crystalline substrates and subjected to two pyrolysis steps at 200 °C and 450 °C before crystallization at 750 °C. Film thicknesses were about 100 nm. For the AgNbO3 end member grown on LaAlO3, the out-of-plane lattice parameter was 3.93±0.01 Å and the full width-half max of the (002)c peak was 0.8°. Phi scan x-ray diffraction indicates that the films are epitaxial. Room temperature electron diffraction illustrates that the films have a tilt sequence along the c-axis similar to that of bulk (a-b-c+/a-b-c- using Glazer notation). When SrRuO3 was used as the bottom electrode, the permittivity of the film was 450 with a loss of 1-2 %. This room temperature permittivity is much higher than the bulk value of 120. The films show a diffuse phase transition at about 550 K which may correspond to the M2-M3 phase transition in bulk materials. However, the permittivity of the thin films is substantially more stable than that of bulk materials, suggesting that there may be a difference in the phase transition sequence. The tunability of the films is 5.7 % and they are not ferroelectric. The capacitance change was 0.72 % while the TCC was 0.0057 %/°C at 125 °C at 10 kHz. For Ag(Ta0.5Nb0.5)O3 films onSrRuO3/LaAlO3, x-ray diffraction indicates that the films are epitaxial with an out-of-plane lattice parameter of 3.92±0.01 Å (compared to 3.929 Å for bulk ceramics). In this case, the electron diffraction data show that the superlattice reflections for the film differ from those shown by bulk ceramics, namely, films show only anti-phase tilting a-b-c-. The temperature dependence of permittivity was significantly different from that of bulk with a diffuse maximum at -190 °C, again suggesting a different phase transition sequence. At 100 kHz, the capacitance change was 5.7 % and TCC -0.066 %/°C at -55 °C while the capacitance change was -12.1 % and TCC -0.148 %/°C at 120 °C. This work, in addition to results of AgTaO3 films, will be presented.
9:00 PM - V11.12
Cross Linkable Phosphorescent Polymer-LEDs Based on a Soluble New Iridium Complex ((Btp)2Ir(III)(acac)-Ox).
Young-Jun Yu 1 , Olga Solomeshch 1 , Vladislav Medvedev 1 , Alexey Razin 1 , Kyu-Nam Kim 2 , Dong-Hoon Choi 2 , Jung-Il Jin 2 , Nir Tessler 1
1 Electrical Engineering, Technion, Haifa Israel, 2 Chemistry, Korea University, Seoul Korea (the Republic of)
Show AbstractPVK is a prototypical host for polymer based phosphorescent OLEDs. We report the photo- (PL) and electroluminescence (EL) properties of phosphorescent organic light emitting diodes (OLEDs) based on poly(vinylcarbazole) (PVK) derivatives doped with cyclometalated Ir(III) complexes. To allow for stable morphology as well as photopatternability, both the host and guest materials were rendered cross-linkable by attaching a cross linking oxetane moiety. Regarding the PVK matrix we also used a new derivative (PVK-Cin) of poly(vinylcarbazole) (PVK) that was prepared by tethering cinnamate pendants to the carbazole group through an octylene spacer. While the use of the oxcetane moieties attached to the ligands of the Ir complex slightly improves the luminescence efficiency, the use of oxcetane derivatized PVK and the associated catalyst result in poor performance. In contrast, the use of the (catalyst free) cinnamate derivatized PVK results in high efficiency cross-linked PLEDs with efficiency higher than 2.5 cd/A. Photopatternability of the new PVK based-polymer was investigated through photocrosslinking reaction under UV light illumination (= 254 nm). The blends of PVK-Cin and a soluble (Btp)2Ir(III)(acac)-Ox were employed for studying a photocrosslinking behavior. We observed that PVK-Cin readily undergoes 2π+2π cycloaddition when exposed to the UV light (λmax = 254 nm) at 110 oC without photoinitiator.
9:00 PM - V11.13
Preparation and Characterization of Chemical Sensor Arrays Using Functional Dyes for the Detection of Volatile Organic Compounds (VOC).
Jonggeon Jegal 1 , Seung Hee Son 1 , Eunsuk Seong 1
1 New Chemistry Division, Korea Research Institute of Chemical Technology, Daejon Korea (the Republic of)
Show AbstractFor clean environment, sensors that can detect the volatile organic compounds (VOCs) in air and are capable to figure out its concentrations have widely been studied, and their performances have been improved. However, still there are some difficulties such as low sensitivity, high humidity effect, and high price. The conventional sensors using Van der Waals force interaction and adsorption as a molecular recognition mechanism usually show a low sensitivity, and their price is high because of the expensive transducer that has to be used for the transformation of the signals. Chemoresponsive dyes based on metalloporpyrine were prepared in this study and used as sensing materials to develop colorimetric sensor arrays that are going to be useful for the detection of low concentration of VOCs in air. Colorimetric sensor arrays were prepared by patterning the chemoresponsive dyes on the microporous poly(vinyliden fluoride) (PVDF) support. The PVDF support was prepared by employing the phase inversion method that has been used for the formation of microporous membranes for water treatment. The prepared sensor arrays were then exposed to the VOCs that was controlled in its concentration, using an apparatus that was designed and prepared in our laboratory, and the color change of the sensor arrays were carefully studied. For the quantitative analysis of the color change of the sensor arrays, an instrument was also designed and fabricated in this study. For this experiment, many different VOCs in different concentrations were used, and the corresponding color pattern change of the sensor arrays were collected to establish data base for the detection of the VOCs. The concentration of VOCs was controlled in ppm range. We also studied the effect of the humidity in the air on the color change of the sensor arrays to see how the humidity affects on the sensitivity of the sensors.
9:00 PM - V11.14
Electrical and Optical Properties of Gold-strontium Titanate Nano-composite Thin Films.
S. Ganti 1 , Y. Dhopade 1 , R. Gupta 1 , K. Ghosh 1 , P. Kahol 1
1 Department of Physics, Astronomy, and Materials Science, Missouri State University, Springfield, Missouri, United States
Show AbstractThin films based on nano-composites have attracted considerable attention for their possible applications in devices and sensors. These nano-composite thin films are formed by embedding metal or semiconductor nano-particles in a host material and they exhibit interesting electrical transport properties. Using pulsed laser deposition technique, we have prepared nano-composite thin films of gold-strontium titanate on quartz substrate. Gold and strontium titanate were used as targets for pulsed laser deposition. Thin films having different compositions were grown at different temperatures. The effect of different composition on their electrical and optical properties has been studied in details. The structural characterizations of the films were done by x-ray diffraction, transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. Transmission electron microscopy as well as atomic force microscopy shows the presence of gold nano-particles in these films. X-ray diffraction and energy dispersive x-ray spectroscopy shows the existence of strontium titanate and gold. Particle size of gold can be varied from 10 nm to 100 nm depending on the growth parameters such as number of pulses, composition and growth temperature. Current-Voltage characteristics and temperature dependent resistivity measurements were made to characterize electrical properties of these films. Electrical properties can be manipulated from metal to insulator through semiconductor by varying the composite. In addition, it is observed that the absorption of visible light increases with increase in gold percentage. This indicates that these nano-composites could also use as active materials for many electronic as well as optical sensors. Detailed structural and electrical characterization of these films will be presented.
9:00 PM - V11.15
Characteristics of WO3 Films Prepared by DCMagnetron Deposition with Interruptions on ITO Glassand Copper Substrates.
Joseph Delhalle 1 , Charlotte Guisset 1 , Fabrizio Maseri 2 , D. Wicky 3 , M. Deepa 4 , Zineb Mekhalif 1
1 Chemistry, University of Namur FUNDP, CES Laboratory, Namur Belgium, 2 , Arcelor-Mittal, Liège Belgium, 3 , University of Liège, Liège Belgium, 4 , National Physical Laboratory, New Delhi India
Show AbstractTungsten trioxide (WO3) is among the most studied materials for their electrochromic properties. The vast majority of reports on the formation of electrochromic WO3 layers deal with CVD and sol-gel approaches. Sputtering techniques, known to have high deposit rates and easy control of the stoechiometry, are also worth investigating, as alternatives to CVD. Our main goal here is the elaboration of an electrochromic device based on tungsten trioxide synthesized by pulsed DC magnetron sputtering with interruption on ITO-coated glass and Cu substrates. The influence of the sputtering parameters on the resulting optical and structural properties of the WO3 films are studied. The nature of the films is analysed by XPS (X-ray photoelectron Spectroscopy), DRX (X-ray diffraction), UV-visible spectroscopy and electrochemistry. Tungsten trioxide films (300 nm thick) were deposited by DC magnetron, with and without interruptions, from a tungsten target on ITO-coated glass and Cu substrates to control the morphology and electrochromic properties of the resulting WO3 films. In the case of ITO-coated glass, which is a poor heat conducting substrate, interruption steps are essential to obtain amorphous WO3 films and proper electrochromic performances. Cu, an excellent electrical and thermal conductor, does not require such steps to yield the required morphology.
9:00 PM - V11.16
Enhanced Contrast Ratios and Fast Switching in Window Type Dual Electrochromic Devices.
Svetlana Vasilyeva 1 , Ece Unur 1 , Ryan Walczak 1 , Benjamin Reeeves 1 , Christophe Grenier 1 , John Reynolds 1
1 Chemistry, University of Florida, Gainesville, Florida, United States
Show AbstractA series of substituted poly(3,4-propylenedioxythiophene) (PProDOT) and poly(3,4-propylenedioxypyrrole) (PProDOP) polymers that exhibit high conductivity, fast electrochromism and excellent switching stability, have been developed. The side-chain derivatization of the conjugated backbone structure improves solution processability of these polymers and makes them air-brush sprayable and potentially printable. Dual polymer window type electrochromic devices (ECDs), using spray-casted electrochromically complementary anodically and cathodically coloring polymers, have been fabricated. Results on the electrochemistry, spectroelectrochemistry, chronoabsorptometry and colorimetry of the individual polymer materials and the dual polymer ECDs will be presented. Different gel electrolyte combinations have been probed to attain the highest switching speeds while maintaining high electrochromic (EC) contrast. The EC contrast of these devices has been optimized by the relative thickness of the two films. Although some dual ECDs show enhanced contrast compared with the initial constituent materials, a significant loss in transmittance of the bleached state of the window devices has been examined. In order to maximize the contrast and transmissivity of ECDs in clear state, a new non-color-changing electroactive transparent polymer (supplied by Ciba Specialty Chemicals) has been used as a counter electrode. These devices demonstrate vivid colors of the working electrochromic polymer materials, which is difficult to achieve in ECDs composed of two electrochromic films.
9:00 PM - V11.17
Unbreakable Solid-Phase Microextraction (SPME) Metallic Fibers and GC Columns.
Isabelle Minet 1 , László Hevesi 1 , Joseph Delhalle 1 , Zineb Mekhalif 1
1 Chemistry , FUNDP Namur, Namur, Namur, Belgium
Show AbstractAlthough the use of the initially designed SPME fibers (J. Pawliszyn,1990) is increasingly gaining in popularity, they present some important drawbacks such as relatively low recommended operating temperature, their instability and swelling in organic solvents, the breakage of the fiber, the stripping of coatings and bending of the needle.The goal of our project is to use stainless steel wires for SPME fibres and stainless steel fine tubes for GC columns. To reach this goal, we have worked out a “grafting from” method for the grafting of a layer of polymer, copolymer or composite materials onto the stainless steel surfaces. The first step is the grafting of a monolayer of ATRP (atom transfer radical polymerisation) initiators, 11-(2-bromo-2-methyl)propionyloxyundecylphosphonic acid, onto the stainless steel wires or onto the inner wall of the fine tubes. Polymerisation from these surfaces is then performed under usual ATRP conditions. The advantages of our method are twofold: the use of stainless steel as support ensures much greater mechanical robustness of the title objects and the onsite polymerisation technique allows for the synthesis of coating layers exhibiting a wide range of affinity towards the compounds to be extracted from various samples (SPME) and / or to be separated and identified (GC). Indeed, these layers can consist of different homopolymers, statistical or block copolymers, as well as the same “doped” by unfonctionnalised carbon nanotubes. Furthermore, since the coated layers are covalently bound to the stainless steel surfaces, good to excellent thermal stabilities are obtained as well as perfect resistance to solvents can be achieved.The so prepared SPME fibers were evaluated for extraction of different classes of compounds (alcohols, BTEX, amino-acids and halomethanes) from aqueous solutions. The optimization of the parameters affecting the extraction efficiency of the target compounds was studied (temperature and time of extraction). The reproducibility of the coating procedure was evaluated resulting in a relative standard deviation lower than 10%. The repeatability for one fiber (n=10) was lower than 5%. The detection limits were lower than 25µg/L, 20µg/L, 15µg/L and 18µg/L for alcohol, BTEX, amino-acids and halomethanes, respectively. Taking into account the amount extracted per unit volume, the stainless steel fibers showed better extraction profiles in comparison with the commercial fibers (PDMS 7µm, PA 30-50µm). The new SPME fibers have a lifetime of over hundred extractions. Thus, it is a promising alternative for low cost analysis, as the proposed fibers are robust and easily and inexpensively prepared. By the same grafting method, some new metallic GC columns were prepared. Different solid phases have shown different affinity towards polar or non-polar compounds.
9:00 PM - V11.19
Microstructure Characterization of Thin Structures After Deformation.
Sabine Weiss 1 , Michael Schymura 1 , Tim Schnauber 1 , Alfons Fischer 1
1 Materials Science, University Duisburg-Essen, Duisburg Germany
Show Abstract9:00 PM - V11.2
Growth of Epitaxial Pb(Zr,Ti)O3 Thick Films on (100)CaF2 Substrates with Perfectly Polar-axis-orientation and their Electrical and Mechanical Property Characterization.
Takashi Fujisawa 1 , Hiroshi Nakaki 1 , Rikyu Ikariyama 1 , Tomoaki Yamada 1 , Mutsuo Ishikawa 1 , Hitoshi Morioka 1 2 , Keisuke Saito 2 , Hiroshi Funakubo 1
1 Department of Innovative and Engineered Materials, Tokyo institute of technology, Yokohama Japan, 2 Application Laboratory, Bruker AXS, Yokohama Japan
Show Abstract9:00 PM - V11.20
Controlled Synthesis and Structure-property Correlations in Vanadium Based Oxides.
Tsung-Han Yang 1 , Wei Wei 1 , Chunming Jin 1 , Roger Narayan 1 , Jay Narayan 1
1 Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina, United States
Show Abstract Vanadium based oxides have several interesting properties, metal to insulator transition (V2O3), and semiconductor to metal transition (VO2), depending upon crystal structure and chemical composition. The most interesting material is vanadium dioxide (VO2) which has a very sharp transition temperature close to 340 K as the crystal structure changes from monoclinic phase (semiconductor) into tetragonal phase (metal phase). This property can be used as the sensor- and memory-type applications in solid state devices. We have grown high-quality epitaxial vanadium oxide (V2O3, VO2) films on sapphire (0001) substrates by pulsed laser deposition and obtained interesting results without further annealing treatments. The epitaxial growth occurred via domain matching epitaxy, where integral multiples of planes matched across the film-substrate interface. We were able to control the phase and crystalline structure of the vanadium oxide by manipulating laser deposition parameters and partial pressure of oxygen. The chemical composition of vanadium oxide changed from V2O3 to VO2 as the oxygen pressure increased from 10-5 to 10-1 torr. We present correlations among resistivity, stoichiometry, microstructure, and characteristics of hysteresis loop for different phases of vanadium oxides. * This research was sponsored by the National Science Foundation
9:00 PM - V11.21
Effect of Substrate-induced Strain on the Electrical and Optical Properties of VO2 Thin Films.
Hyun Koo 1 , Won-Mo Lee 1 , Sejin Yoon 1 , Sung-Hwan Bae 1 , Chan Park 1
1 Materials Science and Engineering, Seoul National University, Seoul Korea (the Republic of)
Show AbstractVanadium dioxide(VO2) has been reported to be the most attractive material for thermochromic windows in which the infrared transmittance changes abruptly at certain temperature. The abrupt change in optical properties of pure VO2 results from the semiconductor-metal phase transition which occurs at ~68°C. Previous experiments showed that it was hard to grow thermochromic VO2 thin films directly on glass substrate, whereas the depositions on crystalline substrates (single crystal or preferred oriented polycrystalline substrate) were easily accomplished. Properties of VO2 thin films deposited on sapphire substrates with different orientations were already reported.[1] Furthermore, VO2 thin films were successfully grown heteroepitaxially on (001) preferred oriented ZnO coated glass.[2] In this work, in order to investigate the effect of substrate-induced strain on the electrical and optical properties of thermochromic VO2 thin films, VO2 films were deposited on substrates with varying lattice parameters which have the same orientation(single crystals of Si, SrTiO3, and Sapphire with (001) orientation) by pulsed laser deposition. XRD was used to analyse both the preferred orientation and the stress of the deposited film. The deposition conditions of the films and the results of XRD and electrical/optical characterization will be presented. The effects of stress on the properties of VO2 thin films on different substrates will be discussed. References.[1] Z.P.Wu and H.Naramoto, “Heteroepitaxial Growth and Phase Transition Properties of Vanadium Dioxide Thin Films on Different Orientations of Sapphire Substrates”, Mat. Res. Soc. Symp. Proc. Vol. 672, 2001[2] Kazuhiro Kato, Pung Keun Song, Yuzo Shigesato and Hidehumi Odaka, “Thermochromic VO2 Films Heteroepitaxially Grown on ZnO Coated Glass by RF Sputtering”, Mat. Res. Soc. Symp. Proc. Vol. 666, 2001
9:00 PM - V11.22
Active Component Fabrication for Low Temperature Co-fired Ceramics (LTCC) Microfluidic Devices.
Wenli Zhang 1 , Nitin Satarkar 1 , James Hilt 1 , Paritosh Wattamwar 1 , Kelly Cummings 1 , Thomas Dziubla 1 , Richard Eitel 1
1 Chemical and Materials Engineering Department, University of Kentucky, Lexington, Kentucky, United States
Show AbstractLow temperature co-fired ceramic (LTCC) technology is a multilayer fabrication technique that has been used for automotive, telecommunication and other applications with high demands on packaging density and reliability. The role of LTCC technology for producing microsystem components and their integration has been increasing for many years. Recently, using LTCC technology in microfluidic system is emphasized due to the ease of fabricating 3D microstructures and capability of integrating fluidic networks with other components in one module. Highly integrated LTCC microsystems have a promising future in microelectronic, biomedical and other applications. The goal of the current work is to develop a toolbox of LTCC microfluidic components and systems. Specifically, three tools are being developed:(1)Laminar flow reactorControlled mixing of two liquids in small volumes is essential in many biomedical and analytical chemistry applications. A LTCC laminar flow reactor has been developed for the controlled synthesis of the anticipant polymer Trolox.(2)Remote controlled valvesIndependent external control of valve operation is required in many microfluidic systems, such as in implantable biomedical applications for drug delivery. A magnetic field – responsive hydrogel nanocomposite material has been integrated into LTCC microfluidc systems as a remote-controlled valve.(3)Active piezoelectric actuatorsPZT thick film piezoelectric layers integrated into LTCC would provide interesting possibilities for application in actuators and sensors. The optimization of processing and piezoelectric properties of PZT layers co-fired on LTCC materials will enable the fabrication of active piezoelectric devices and sensors including micropumps.The successful design and optimization of these various components will provide key functionalities required for future highly integrated microdevices and microsystems.
9:00 PM - V11.23
Raman Spectroscopy under Tensile Loading for Evaluating Surface Stress on Single-Crystalline Silicon Microstructures.
Mamoru Komatsubara 1 , Takahiro Namazu 1 , Nobuyuki Naka 2 , Shinsuke Kashiwagi 2 , Kunio Ohtsuki 2 , Shozo Inoue 1
1 , Department of Mechanical and Systems Engineering, University of Hyogo, Japan, Himeji Japan, 2 , Semiconductor Systems R&D Department, HORIBA Ltd., Japan, Kyoto Japan
Show AbstractRecently, micro components made of single crystal silicon (SCS) in electron devices and microelectromechanical systems (MEMS) have being shrunk in size as the rapid progress in semiconductor microfabrication technology. Evaluation of stress and strain applied to the components leads to improvement of the performance and reliability of such the silicon devices. Raman spectroscopy is a promising method for measuring local stress on SCS. It has advantages such as (1) non-destructive measurement, (2) short measurement time, and (3) comparatively high spatial resolution less than 1 μm. With shrinking the pattern size, however, it is difficult to apply Raman spectroscopy to sub-microscale structures like a channel and shallow trench isolation (STI) because of limitation of its spatial resolution. In addition, the stress status around the edge of those minute structures is complicated as tensile, compressive, and shear stresses occur simultaneously. Consequently, evaluating the magnitude and component of stress on these structures is technically difficult.In this paper, a novel experimental analysis method for evaluating surface stress distribution on SCS microstructures using laser Raman spectroscope is presented. A biaxial tensile tester that was newly developed for film specimens was employed to apply a uniaxial stress to SCS specimen. The tester consists of 4 sets of piezoelectric actuator built in the actuator case, linear variable differential transformer (LVDT), load cell, and specimen holder. The tensile specimen includes the 300 μm-wide and 3 mm-length gauge section with 270 nm-height and 4 μm-square convex SCS structures for evaluation of stress distribution. The specimen is oriented along the [110] direction in the (001) plane, which corresponds to the principal stress direction during the test.Raman spectra around the convex were measured under a constant tensile stress. The stress distribution was compared with that from finite element analysis (FEA). The shape of Raman spectra nearby the edge of the convex was asymmetry. So, we performed two-curve fitting to these spectra. The stress distribution estimated from two peak positions was much closer to FEA results than that from one peak position that is typically employed. Consequently, stress information from the top and bottom surfaces of convex edge could be obtained separately. In addition, partial-least square (PLS) analysis was conducted. For this analysis, explanatory variables were Raman spectral parameters, such as peak position, peak intensity, and full width at the half maximum (FWHM). Response variables were the stress distributions from FEA. The stress distributions from PLS analyses were in good agreement with those from FEA. The PLS analysis enabled us to determine stress component of SCS microstructures. The Raman spectroscopy with the two-curve fitting and PLS analyses would be effective method for evaluation of local surface stress on SCS microstructures.
9:00 PM - V11.24
Microstructure and Service Life of Silver Copper Oxide Contact Materials After Reactive Synthesis Fabrication and Severe Plastic Deformation.
XiaoLong Zhou 1 , JianChun Cao 1 , JingChao Chen 1 , Kunhua Zhang 2
1 , Kunming University of Science and Technology, KunMing China, 2 , Kunming Institute of Precious Metal, kunming China
Show Abstract9:00 PM - V11.25
High Dielectric Permittivity and Low Percolation Threshold in Nanocomposites Based on Poly(vinylidene fluoride) and Exfoliated Graphite Nanoplate.
Jintu Fan 1 , Fuan He 1
1 Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hong Kong, Hong Kong, China
Show Abstract9:00 PM - V11.26
Undec-10-ene-1-thiol Multifunctional Molecular Layer as a Junction between Inorganic and Organic Coatings on Steel.
Zineb Mekhalif 1 , François Berger 1 , Joseph Delhalle 1
1 Chemistry and Electrochemistry of Surfaces, University of Namur FUNDP, Namur Belgium
Show Abstract9:00 PM - V11.3
Structural and Electrical Characterization of Highly Oriented Lead-free (K0.5 Na0.5)NbO3 (KNN) Thin Films by Chemical Solution Deposition.
Chiwon Kang 1 , Jung-Hyun Park 1 , Dongna Shen 1 , Minseo Park 2 , Dong-Joo Kim 1
1 Materials Research and Education Center, Auburn University, Auburn , Alabama, United States, 2 Department of Physics, Auburn University, Auburn , Alabama, United States
Show Abstract9:00 PM - V11.4
Electrophoretic Deposition of Lead free Piezoelectric (K0.5Na0.5) NbO3 Thick Films and its Characterization.
Hosang Ahn 1 , Dong-Joo Kim 1
1 Materials Eng., Auburn Univ., Auburn, Alabama, United States
Show AbstractHosang Ahn, Dong-Joo KimMaterials Education and Research Center, Auburn University, Auburn AL 36849 USACeramic thick films with good piezoelectric and ferroelectric properties have drawn a lot of interests in microdevices such as inkjet head, microfluidic device, sensors and actuators. In biocompatible applications, current lead containing PZT thick films are not suitable. From this demanding to develop lead free piezoelectric materials, (K0.5Na0.5) NbO3 has been investigated for an alternative material due to its high curie temperature, good piezoelectric and electromechanical properties. In processing aspect, electrophoretic deposition has many advantages to make ceramic thick films. Films can be grown with relatively fast deposition rate, and this process can be easily adapted to produce complex shape of substrate without high cost of the apparatus. In this study, (K0.5Na0.5) NbO3 (abbreviated as KNN later) films ranging from 50 to 250 um thickness were deposited on different substrates such as stainless steel, alumina and high temperature stainless steel, Inconel. KNN powder was synthesized by ball milling from raw materials, K2CO3, Nb2O5, and Na2CO3 to obtain the final ratio of 1:1:2. Calcination was performed for 10 hours at 850 °C and sintered at different temperature 900°C, 950°C, 1000°C, 1050°C and 1100°C to reach the densest microstructure. Sintered powder was ball milled again and the average powder size was around 1µm. Based on the electrophoretic mobility of particles in solution, distinct voltage and deposition time were investigated as variables to find the relationship between applied DC voltage, deposition time and film thickness. Empirical conditions to attain the best properties in thick films are proposed.
9:00 PM - V11.5
Effect of the Substrates on Mechanical and Electrical Properties of Pb(Zr0.52Ti0.48)O3 Thin Films.
Dan Liu 1 , Sang H Yoon 1 , Bo Zhou 1 , Barton C Prorok 1 , Dong-Joo Kim 1
1 Materials Engineering, Auburn University, Auburn, Alabama, United States
Show AbstractPZT thin films are widely used in microelectromechanical systems due to their excellent piezoelectric properties. Since the piezoelectric properties of PZT thin films are influenced by the mechanical coefficients, designing MEMS devices should understand the scaling effects of mechanical properties of PZT thin films. In this paper, we investigated the effects of the substrates and crystalline orientations on the mechanical properties of PZT thin films. Electric properties of PZT thin films were also measured. The PZT thin films were deposited by sol-gel method on platinized silicon substrates with different types of layer materials such as silicon nitride, silicon oxide and alumina. The crystalline orientations of PZT films were controlled by combined parameters of a chelating agent and pyrolysis temperature. Nanoindentation CSM (continuous stiffness measurement) technique was employed to characterize the mechanical properties of those PZT films. It was observed that (001/100)-oriented films show higher Young’s modulus compared with (111)-oriented films indicating clear dependence of film orientation while the hardness exhibits less dependence of the orientation. In order to characterize the influence of substrates on the mechanical properties of PZT thin films, the film-substrate structures were divided into two groups: soft/harder and hard/softer type structure. In the case of soft/harder structure (PZT thin film on SiNx or Al2O3-based substrate), we may obtain intrinsic mechanical properties of the PZT thin films according to the one-tenth ‘rule of thumb’, however, the substrate effect will be inevitable even for indentation depths less than 10 to 20% of film thickness for the hard/softer structure (PZT thin film on SiO2 based-substrate). Finally, no significant influence of the film thickness was found on the mechanical properties of those films. The effects of substrates on electrical properties of PZT thin films will also be presented.
9:00 PM - V11.6
Piezoelectric Response of Lanthanum Doped Lead Zirconate Titanate Films for Micro Actuators Application.
Takashi Iijima 1 , Bong-yeon Lee 1 , Seiji Fukuyama 1
1 Research Center for Hydrogen Industrial Use and Storage, National Institute of Advanced Industrial Science and Technology, Tsukuba Japan
Show AbstractIn the field of the micro-scale smart systems, high performance micro actuators are demanded. Therefore, static actuators are well developed as the micro actuator, while the structure of the micro-static actuator is very complicated and the driving voltage is relatively high. To overcome these subjects of the micro-static actuators, piezoelectric film micro actuators such as lead zirconate titanate (PZT) are investigating. However, the piezoelectric related longitudinal displacement of the PZT films shows the butterfly shape hysteresis curves under a bipolar applied electric field. This displacement hysteresis is not good for the precise actuation of the micro smart system. In the case of the piezoelectric bulk ceramics, it is well known that a hysteresis of the piezoelectric longitudinal displacement of the lanthanum (La) substitute lead zirconate titanate (PLZT) decrease with increasing of lanthanum substitution amount. In this study, to clear the possibility of the micro actuator application of the PLZT films, the effect of La substitution for the PZT films on the piezoelectric response were investigated. PLZT films are prepared using a chemical solution deposition process. Nominal compositions of the 10% Pb excess PLZT precursor solutions were controlled like La/Zr/Ti= 0/65/35, 3/65/35, 6/65/35, and 9/65/35. These precursor solutions were deposited on the Ir/Ti/SiO2/Si substrates, and the thickness of the PLZT films was controlled 2μm. 10 to 20-μm-diameter Pt top electrodes are formed with a sputtering and a photolithography process. The polarization- field (P-E) hysteresis curves and the longitudinal displacement curves were measured with an atomic force microscope (AFM) connected with a ferroelectric test system. With increasing La substitution amount, the P-E hysteresis curves became slim shape, and remnant polarization (Pr) and maximum polarization (Pmax) decreased. The hysteresis of the piezoelectric longitudinal displacement curves also decreased with increasing La substitution amount. However, total amount of the displacement under bipolar electric field did not show remarkable difference with various La substitutions. In the case of unipolar field, the longitudinal piezoelectric constant measured with AFM, which was defined as AFM d33, was AFM d33= 113pm/V at 6/65/35. This amount was almost equal to that of PZT films at morphotropic phase boundary (MPB: 0/53/47).
9:00 PM - V11.7
Demonstration of Micro-cantilever Devices using Pb(Ti,Zr)O3 Thin Films Sol-gel Processed on Nanocrystalline Diamond Thin Films.
Jeung-hyun Jeong 1 , Jong-Keuk Park 1 , Ju-Heon Yoon 1 2 , Kyu-Won Hwang 1 , Wook-Seong Lee 1 , Young-Joon Baik 1
1 Thin Film Materials Research Center, Korea Institute of Science and Technology, Seoul Korea (the Republic of), 2 Department of Materials Science and Engineering, Korea University, Seoul Korea (the Republic of)
Show Abstract9:00 PM - V11.8
Harmonic Analysis of AlN Piezoelectric Mesa Structures.
Madhulika Mazumdar 1 , A. Kabulski 2 , R. Farrell 2 , Sridhar Kuchibhatla 2 , V. Pagan 2 , D. Korakakis 2
1 Computer Science, Davis & Elkins College, Elkins, West Virginia, United States, 2 Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, West Virginia, United States
Show Abstract9:00 PM - V11.9
Thermal Degradation and Aging of High Temperature Piezoelectric Ceramics, Period- Aug'07 to Nov'08.
Sunil Gotmare 1 , Richard Eitel 1
1 Chemical and Material Science Engineering, University of Kentucky, Lexington, Kentucky, United States
Show AbstractPiezoelectric materials have numerous applications like ultra high temperature accelerometers, pressure, flow and NDT transducers, acoustic emission, ultrasonic cleaning, welding, high voltage generators, medical therapy etc. The commonly used piezoelectric material, PZT continues to dominate the commercial market for piezoelectric actuators applications. Large piezoelectric co-efficient, and large coupling factor make this material suitable for several applications. The primary limitations of PZT are the lower Curie temperature Tc <360 deg C and rapid thermal degradation above 200 deg C.Continuing efforts are focused on the development of piezoelectric materials suitable for high temperature applications. These materials will be very useful for making sensors for space exploration, electric aircraft, oil and geothermal well drilling tools, oil & gas pipeline health monitoring and automotive smart brakes. Many of these applications require an operational temperature higher than 200 deg C. Recently material based on (X)Bi(Me)O3-(1-x)PbTiO3 developed with Tc~460 deg C, and d33~500 pC/N compared to TC~360 deg C and d33~370 pC/N of pure PZT. Enhanced room temperature properties and higher transition temperature makes this material interesting for further investigation as a high temperature piezoelectric material.In the current work thermal degradation and aging behavior of high temperature piezoelectric material BS-PT will be compared with the commonly used PZT. The MPB and tetragonal compositions with and without modification of accepter dopant will be used for the investigation. PZT and BSPT ceramic powders were prepared by solid state synthesis method. Reagent grade metal oxides and carbonate (ZrO2, TiO2, Bi2O3, Sc2O3, and PbCO3) were used as starting materials. Fe2O3 and MnO2 were used as dopant for PZT and BSPT respectively. The powders were pressed in pellets and then sintered at various temperatures in the range of 1000 to 1300 deg C. The phases of calcined and sintered samples were identified by XRD using CuKα radiation. Density, porosity, and grain size measurements were carried out to optimize sintering parameters to reduce microstructural contributions to properties variation between different compositions. Sintered pellets were ground parallel and conductive Ag electrode was applied for measurement of dielectric properties. Electrode pellets were poled at 100 deg C for 10 min under 30-40 kV/cm and thermally aged in a controlled atmosphere oven at 200-300 deg C. The pellets will be characterized for dielectric and piezoelectric properties, initially at weekly interval and then monthly for the duration of study. Results will be interpreted considering prior degradation and aging studies in piezoelectric. This study will determine the promise of the BSPT system for high temperature piezoelectric applications and lead to an improved understanding of thermal degradation of the MPB, tetragonal and acceptor doped piezoelectric materials.
Symposium Organizers
Ji Su NASA Langley Research Center
Li-Peng (Leo) Wang TricornTech Corporation
Yasubumi Furuya Hirosaki University
Susan Trolier-McKinstry The Pennsylvania State University
Jinsong Leng Harbin Institute of Technology
V12: Shape Memory
Session Chairs
Yasubumi Furuya
Jinsong Leng
Thursday AM, December 04, 2008
Commonwealth (Sheraton)
9:15 AM - **V12.1
Microstructures and Enhanced Properties of SPD-processed TiNi Shape Memory Alloy.
Koichi Tsuchiya 1
1 , National Institute for Materials Science, Tsukuba Ibaraki Japan
Show Abstract Recently deformation-induced amorphization of TiNi shape memory alloys has been investigated extensively using cold rolling, shot peening and high pressure torsion. Recently we have reported the amorphization of TiNi wire. Wires of Ti-50.9mol%Ni alloys were deformed severely by cold drawing. Changes in mechanical properties and microstructures were investigated by means of X-ray diffractometry (Cu-Kα, TEM observations (200 kV), micro-hardness measurements and tensile tests at room temperature. X-ray diffractometry and TEM observations revealed that the severely deformed wires were composed of the mixture of amorphous and nanocrystalline B2 phase. Hardness measured on the cross-section for the as-draw amorphous/B2 TiNi were over 600Hv. The hardness value further increased by aging at 473 K for 3.6 ks. The tensile stress-strain curves had no-stress plateau, yet exhibited over 3% recoverable strain. Slope of the initial part of the tensile-stress strain curves increased with the reduction in area. The wire deformed aged at 573 K for 3.6 ks exhibited the tensile strength of 2.4 GPa, 5 % recoverable strain and apparent elastic modules of 71 GPa. Such high strength TiNi wires can be useful in medical devices.
9:45 AM - V12.2
Numerical Study on Fretting Fatigue Life of NiTi Shape Memory Alloys.
Xiaoxue Wang 1 , Rongqiao Wang 1
1 School of Jet Propulsion, Beihang University(Beijing University of Aeronautics and Astronautics), Beijing, Beijing, China
Show Abstract10:00 AM - V12.3
Shape-memory Polymer Composite and Its Application.
Jinsong Leng 1 , Haibao Lv 1 , Yanju Liu 1 , Shanyi Du 1
1 Centre for composite materials, Harbin Institute of Technology, Harbin China
Show Abstract10:15 AM - V12.4
Dimensional Analysis of Fracture Induced by Cold Rolling in Shape Memory alloy/polymer Composites.
Barbara Calcagno 2 , Kevin Hart 3 , John Springmann 3 , Wendy Crone 1 2 3
2 Materials Science, University of Wisconsin - Madison, Madison, Wisconsin, United States, 3 Engineering Mechanics, University of Wisconsin - Madison, Madison, Wisconsin, United States, 1 Engineering Physics, University of Wisconsin - Madison, Madison, Wisconsin, United States
Show AbstractThe fracture behavior of NiTi shape memory alloy in a polymeric composite fabricated by rolling and folding was investigated. NiTi/polypropylene, NiTi/polycarbonate, and NiTi/high density polyethylene composites exhibit different fracture patterns when the composites are manufactured by extensive cold rolling and folding. Particle size distributions obtained by fracturing the metals embedded in the polymer are related to the properties of the constituents and to the characteristic variables of the rolling process. Study of the many variables governing the process using dimensional analysis gives a strong correlation between the composite strain and the dimensionless nip gap parameters. Beyond the direct impact of these results on smart composites materials, there are implications for food processing and the formation of geological structures.
10:30 AM - V12.5
Shape Memory Actuation by Resistive Heating in Polyurethane Composites of Carbonaceous Conductive Fillers.
Sedat Gunes 1 , Guillermo Jimenez 1 , Sadhan Jana 1
1 Department of Polymer Engineering, The University of Akron, Akron, Ohio, United States
Show AbstractThe effectiveness of carbonaceous, electrically conductive fillers in shape memory actuation of polyurethanes by resistive heating was evaluated in this work. Specifically, the dependence of electrical resistivity on specimen temperature and imposed tensile strains was determined for shape memory polyurethane (SMPU) composites of carbon nanofiber (CNF), oxidized carbon nanofiber (ox-CNF), and carbon black (CB). The SMPU composites with crystalline soft segments were synthesized from diphenylmethane diisocyanate, 1,4-butanediol, and poly(caprolactone)diol in a low-shear chaotic mixer and in an internal mixer. The materials synthesized in the chaotic mixer showed higher soft segment crystallinity and lower electrical percolation thresholds. The soft segment crystallinity reduced in the presence of CNF and ox-CNF; although the reduction was lower in the case of ox-CNF. The composites of CB showed pronounced positive temperature coefficient (PTC) effects which in turn showed a close relationship with non-linear thermal expansion behavior. The composites of CNF and ox-CNF did not exhibit PTC effects due to low levels of soft segment crystallinity. The resistivity of composites of CNF and ox-CNF showed weak dependence on strain, while that of composites of CB increased by several orders of magnitude with imposed tensile strain. A corollary of this study was that a high level of crystallinity may cause a PTC effect and prevent any actuation through resistive heating. However, a carefully tailored compound which has reduced crystallinity and which requires minimum amount of filler may prevent PTC phenomenon and could supply necessary electrical conductivity over the operating temperature range, while offering enough soft segment crystallinity and rubberlike properties for excellent shape memory function.
10:45 AM - V12.6
Ultra-high damping Shape Memory Alloys Composites.
Jose San Juan 1 , Mariano Barrado 1 , Gabriel Lopez 2 , Maria No 2
1 Fisica Materia Condensada, Universidad del Pais Vasco, Bilbao Spain, 2 Fisica Aplicada II, Universidad del Pais Vasco, Bilbao Spain
Show AbstractV13: Ferromagentic Shape Memory
Session Chairs
Ichiro Takeuchi
Koichi Tsuchiya
Thursday PM, December 04, 2008
Commonwealth (Sheraton)
11:30 AM - V13.1
Sensing Shape Recovery using Conductivity Noise in Thin Films of NiTi Shape Memory Alloys.
U. Chandni 1 , Arindam Ghosh 1 , H. Vijaya 2 , S. Mohan 2 , Amrita Singh 1
1 Physics, Indian Institute of Science, Bangalore, Karnataka, India, 2 Instrumentation, Indian Institute of Science, Bangalore, Karnataka, India
Show Abstract11:45 AM - V13.2
Effect of Aging on the Magnetic Behavior of Magnetic Shape Memory Ni-Mn-Al Heusler Alloys.
Cem Topbasi 1 , M. Vedat Akdeniz 1 , Amdulla O. Mekhrabov 1
1 Metallurgical & Materials Engineering, Middle East Technical University, Ankara Turkey
Show AbstractMagnetic shape memory (MSM) alloys exhibiting magnetic field induced strains up to 10% have received considerable attention in recent years due to their unique combination of ferromagnetism and structure. A promising alternative for the prototype Ni-Mn-Ga Heusler alloy system in MSM applications is the Ni-Mn-Al Heusler alloy system. Ni-Mn-Al alloys offer better mechanical properties, cost less and are easier to produce. Ni-Mn-Al alloys exhibit similar martensitic transformations to the Ni-Mn-Ga alloys. Nevertheless, the ferromagnetic L21 phase which is readily stabilized in Ni-Mn-Ga alloys could not be obtained in Ni-Mn-Al alloys in previous studies as a single phase due to the significantly low B2↔L21 transition temperature of these alloys. All the Ni-Mn-Al alloys were reported to contain a mixture of the L21 (ferromagnetic) and B2 (antiferromagnetic) phases. As a result of this, Ni-Mn-Al alloys exhibit lower magnetic field induced strains than the Ni-Mn-Ga alloys. The present study aimed to investigate the effect of low temperature aging for various time periods (12, 24 and 48 days) on the stabilization of the L21 (ferromagnetic) phase in Ni50Mn50-xAlx alloys (10〈x〈 30) by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). We have shown that all the as-cast Ni50Mn50-xAlx(x=10, 20, 25 and 30) Heusler alloys exhibit an antiferromagnetic behaviour at room temperature and low temperature aging (at 660 K) introduces ferromagnetism in these alloys as a result of the establishment of ordering at the Mn-Al sublattice. Magnetization and XRD measurements revealed that there is no significant change in terms of atomic and magnetic ordering for the 24 and 48 day-aged Ni50Mn50-xAlx(x=10, 20, 25 and 30) alloys. This suggests that further ordering at the Mn-Al sublattice has not developed significantly in that period or a metastable equilibrium between the B2 (antiferromagnetic) and L21 (ferromagnetic) phases was reached. In addition to that, we have determined the trends of Curie and Neel Temperatures with electron concentration for Ni50Mn50-xAlx (10〈x〈30) alloys. We have also showed that a transition from the cubic L21 -type structure to the tetragonal L10 -type structure occurs with increasing Mn content or electron concentration in Ni50Mn50-xAlx (0〈x〈 50) alloys at room temperature.
12:00 PM - V13.3
Hysteresis in Thermal- and Magnetic Field-Induced Martensitic Phase Transitions in Ni-Mn-Sn Heusler Alloys.
Patrick Shamberger 1 , Fumio Ohuchi 1
1 Materials Science & Engineering, University of Washington, Seattle, Washington, United States
Show AbstractMagnetic field-induced first-order phase transitions result in a number of functional material properties, including the metamagnetic shape memory effect [1] and the “giant” magnetocaloric effect [2]. These properties can be used in high-performance magnetic field controlled actuators and magnetic refrigerators, respectively. Ni-Mn-X (X=Ga, In, Sn…) Heusler alloys exhibit this type of behavior, having a martensitic phase transition at a critical temperature, Tcr, which is controllable by alloying (e.g., [3]). Applying a magnetic field while at temperatures near Tcr induces a phase change in these materials, resulting in a strain or a magnetic entropy change, ΔSM. However, the martensitic transition in Ni-Mn-X alloys is typically associated with hysteresis, which both reduces the fraction of phase transformed for a given field and diminishes the amount of useful work that a material can perform (hysteretic loss).Here, we have investigated the temperature and field-dependent behavior of a polycrystalline Heusler alloy with the composition Ni50.5Mn34.0Sn15.6, around its martensitic transition. Specifically, we have characterized the fraction of martensite and parent (Heusler phase) present along a variety of complex temperature and magnetic field paths, using magnetization as a proxy for the fraction of phases present. We present these results and discuss: 1) the thermal- and magnetic field-induced hysteresis behavior, and 2) the effect of this hysteresis on the magnetocaloric effect of the material. Hysteresis behavior is interpreted in terms of boundary friction phenomenological theory. We demonstrate that both temperature and magnetic field are thermodynamically equivalent driving forces for the phase transition and result in complementary hysteresis behavior that can be linked through the Clausius-Clapeyron equation. This relationship may be used to collapse a complex temperature and magnetic field path onto a single variable, for the purpose of constructing a predictive description (e.g., a Preisach model) of the hysteresis. The observed hysteresis causes only ~5% of the alloy to reversibly transform between the martensite and the parent Heusler phase under application and removal of a 9 T magnetic field. Therefore, only ~5% of the heat of reaction of the martensitic phase change contributes to the magnetocaloric effect (ΔSM) of the material [4]. Our results suggest that the hysteresis behavior of a material may be more critical in evaluating its functional magnetocaloric effect than its thermodynamically reversible magnetic entropy change.[1] O. Tegus et al., Nature, 415 (2002) 150-152.[2] R. Kainuma et al., Nature, 439 (2006) 957-960.[3] Y. Sutou et al., Appl. Phys. Lett., 85 (2004) 4358-4360.[4] V.K. Pecharsky et al., Phys. Rev. B, 64 (2001) 144406.
12:15 PM - V13.4
An Investigation on Martensitic and Magnetic Phase Transitions in Ferromagnetic Ni-Fe-Al Heusler Alloys.
Nagehan Duman 1 , Amdulla Mekhrabov 1 , M. Vedat Akdeniz 1
1 Metallurgical and Materials Engineering, Middle East Technical University, Ankara Turkey
Show AbstractFerromagnetic shape memory alloys (FMSMAs) have received much attention as candidate actuator materials that can be driven by a magnetic field and many ferromagnetic alloy systems such as Ni-Mn-Ga, Ni-Mn-Al and Co-Ni-Ga have been developed in the recent years. Tunability of martensitic and magnetic phase transition temperatures and ductility of these alloys are important in FMSMA applications. From this aspect, therefore, we have investigated a ternary ferromagnetic Heusler alloy system, Ni50Fe50-xAlx (10〈x〈40) due to its promising properties for the future structural applications through an appropriate choice of composition and heat treatment. In this FMSMA system, with increasing Fe content, the martensitic transition temperature decreases while magnetization and magnetic transition temperature (Curie temperature) increases. Furthermore the atomic ordering at the Fe-Al sublattice which affects these transition temperatures was controlled by adjusting the annealing temperatures to increase the amount of L21 phase. To optimize all these properties of Ni50Fe50-xAlx (10〈x〈40) alloys synthesized by arc melting technique, the effects of composition and annealing temperature on the martensitic and magnetic transition temperatures, magnetic behaviour and microstructure in Ni50Fe50-xAlx (10〈x〈40) Heusler alloys were investigated with X-ray diffraction (XRD), thermal analysis and vibrating sample magnetometry (VSM), scanning electron microscopy (SEM). Experimental results on the effect of different compositions and annealing temperatures were discussed.
12:30 PM - V13.5
A Theoretical Model of Ferromagnetic Shape Memory Thin Film In-plane Actuators.
Vesselin Stoilov 1
1 Mechanical Automotive and Materials Engineering, University of Windsor , Windsor, Ontario, Canada
Show AbstractThis paper presents a model of reorientation of martensitic variants in ferromagnetic shape memory alloys thin films subjected to combined magneto-mechanical loading. The model is based on the multiscale model introduced by Stoilov (Smart Mat. Str., 2007), and allows for complete description of the second order phase transformations in FSMA thin films under multiaxial loading. The magnetic and crystallographic aspects of the twin-boundary motion responsible for this phenomenon were described. Closed form expressions for the twin boundary velocity and overall macro displacements were derived. Nucleation of variants and propagation of twin boundaries were investigated under combined magneto-mechanical loading and compared to recent experiments. The model showed that phase boundary motion can result in significant deformation and allowed estimation of the overall deformation in a magnetic shape memory material. The results of the simulation of the reorientation behavior and macroscopic response of FSMA thin films subjected to combined magneto-mechanical loading showed possibility to reach powerful actuation keeping the same geometric dimensions at lower magnitudes of the actuation magnetic field. An assessment of mechanical output for the FSMA thin film actuators has been done, proving that the suggested model provides a viable tool for exploring the microscale dynamics of martensitic variants and their implications on macroscopic behaviour of FSMA thin films, and it may be very valuable in the design of advanced microdevices.
Thursday PM, December 04, 2008
Commonwealth (Sheraton)
2:30 PM - **V14.1
RF Microwave Switches Based On Reversible Metal-Semiconductor Transition Properties Of VO2 Thin Films: An Attractive Way To Realise Simple RF Microelectronic Devices.
Frederic Dumas-Bouchiat 1 2 3 , Corinne Champeaux 1 , Alain Catherinot 1 , Julien Givernaud 2 , Aurelian Crunteanu 2 , Pierre Blondy 2
1 , SPCTS, Limoges, FRANCE, France, 2 , Xlim, Limoges, FRANCE, France, 3 , Néel Institut, Grenoble, FRANCE, France
Show AbstractVanadium dioxide is a famous material exhibiting an abrupt reversible semi-conductor to metal (SC-M) transition at a critical temperature, Tt ≈ 341K. By monitoring temperature, VO2 can refind metallic or semi-conductor properties, as well. These thermochromic properties, close to room temperature, make VO2 an attractive material candidate in RF switching devices.In this paper, we present microwave switching devices based on SC-M thin film transition which are developped on two types of substrates (C-plane sapphire and SiO2/Si) and in both shunt and series configurations. Under thermal activation, the VO2-based switches achieve up to 30-40 dB average isolation of the radio-frequency (RF) signal on a very wide frequency band (500 MHz-35 GHz) with weak insertion losses. Furthermore, these VO2-based switches can be electrically activated. The commutation times which are calculated to be around 700ns (on a based thermal model) and measured around 100ns. These experimental results appear very promising compare to conventionnal RF Micro-Electro-Mechanical System (MEMS) which work in a shorter frequency domain (around 10-15 GHz) and with a longer commutation time.Finally these VO2-based switches are integrated in the fabrication of innovative tunable band-stop filters which consist in a transmission line coupled with four U-shaped resonators and operate in 11-13 GHz frequency range.
3:00 PM - V14.2
Lateral V/VOx/V Tunnel Junctions Formed by Anodic Oxidation.
David Kirkwood 1 , Kevin West 1 , Jiwei Lu 1 , Stuart Wolf 1
1 , University of Virginia, Charlottesville, Virginia, United States
Show AbstractAnodization has been found to be a simple and cost effective technique to produce oxide films of many transition metals. In this work, we have used anodic oxidation as a means of fabricating lateral V/VOx/V junctions. Vanadium wires grown by ion beam deposition were patterned by lithography and an active working window was defined on the wire. VOx was then grown under galvanostatic control in a two electrode electrochemical micro-cell with a platinum counter electrode and aqueous boric acid electrolyte. A constant current of approximately 100 μA/cm2 was maintained through the cell for various amounts of time. Electrical measurements of the resulting V/VOx/V junctions indicate a metal to insulator transition (MIT) near 340 K that is similar to the structural phase transition and accompanied MIT known to occur in crystalline VO2. A 4-fold change in resistance is observed in the junctions. Below this transition temperature a non-linear IV characteristic is observed on junctions with a size of 5 μm by 15 μm suggesting that the anodized VOx film behaves like a tunneling barrier.
3:15 PM - V14.3
A Novel Approach Towards Integration of Vanadium Oxide (VO2) Thin Films on Si(100) for Thermal Switching Devices Applications.
Alok Gupta 1 , Tsung-Han Yang 1 , Ravi Aggarwal 1 , Jagdish Narayan 1
1 , Department of Materials Science & Engineering, North Carolina State University, Raleigh, North Carolina, United States
Show Abstract4:00 PM - **V14.4
Epitaxial Piezoelectrics For Energy Scavenging.
P. Shafer 1 , Ramamoorthy Ramesh 1
1 Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley, Berkeley, California, United States
Show Abstract4:30 PM - V14.5
In-Plane Poisson’s Ratio Measurement Method for Thin Film Materials by On-Chip Bending Test with Optical Interference Image Analysis.
Mitsuhiro Tanaka 1 , Takahiro Namazu 1 , Shozo Inoue 1
1 Mechanical and System Engineering, University of Hyogo, Himeji, Hyogo, Japan
Show AbstractMicro-Electro-Mechanical Systems (MEMS) that is a derivative of semiconductor industry becomes one of the common technologies in today’s micro-device communities. Almost of MEMS includes micro/nanoscale components made of film materials. To improve the reliability of MEMS, structural materials have to be tested in a usage scale and their properties must be revealed.In this paper, we present a novel evaluation technique for in-plane Poisson’s ratio of thin film materials by on-chip bending test method that has been proposed. When rectangular beam specimen is bent with constant radius of curvature along its longitudinal direction, anticlastic curvature occurs in transversal direction due to the Poisson coupling. Thereby, the specimen deforms to saddle-like shape. The profile of saddled shape is represented as a hyperbolic pattern with an asymptote. The angle, θ, of asymptote to transversal direction of specimen have a relation with Poisson’s ratio of the material expressed as tanθ^2=ν. This relation indicates that, if the angle, θ, can be measured, Poisson’s ratio is able to be evaluated.We have designed the device that can apply bending to a film specimen. The device consists of a film specimen, coupled loading levers, torsion bars, and frame. With application of external loads to levers, torsion bars that are connected with levers are twisted, then levers rotate around torsion bars; consequently bending force is applied to a film specimen. Finite element analysis has been conducted for an optimum design of a test chip. We have fabricated the test chip designed through conventional micro machining technologies. The test chip has been fabricated from SOI wafer with device layer thickness of 10μm. The longitudinal direction of specimen has been oriented to the [110] direction in {100} plane.The testing apparatus consists of needles for loading, X-Y-Z positioning stage for the needles, a heating system, and objective lens with dual beam interferometer. The profile of bent specimen has been obtained by interference fringe pattern. To accurately locate the asymptote, blob analysis was conducted. At first, the closure line of blob was defined, and numerical calculation was then performed at each line to derive the points which the asymptote was laid on. The angle, θ, was finally obtained by slope of the line which can be drawn from the points.We confirmed deformation to anticlastic curvature of bent specimen by obtained the hyperbolic interference patterns. Average measured angle was 15.4 degrees, resulting in in-plane Poisson’s ratio of 0.076. The Poisson’s ratio had an error of 18% from that of ideal value, 0.064. However, due to the measured principle for an isotropic material, this error has occurred because of strong anisotropy in single-crystal silicon (SCS).We are now investigating the temperature dependency on the Poisson’s ratio of SCS. Also, measurement results of poly-crystalline silicon will be reported as well.
4:45 PM - V14.6
Mechanical Characteristics of Al-Si-Cu Structural Films by Uniaxial Tensile Test with Elongation Measurement Image Analysis.
Hiroki Fujii 1 , Takahiro Namazu 1 , Yasushi Tomizawa 2 , Shozo Inoue 1
1 Mechanical and Systems Engineering, University of Hyogo, Himeji Japan, 2 Mechanical Systems Laboratory, Corporate Research & Development Center, Toshiba Corporation, Kawasaki Japan
Show AbstractMechanical properties of constituent materials for MEMS devices have to be investigated to design the devices towards their high-performance and reliability. In this paper, a novel tensile test technique with elongation measurement image analysis system for thin film materials is presented. We focused on investigating material properties of Al-Si-Cu structural film at intermediate temperatures and its fatigue behavior.The compact uniaxial tensile tester consists of PZT actuator, load cell, CCD camera, specimen holder, and heating system. The specimen consists of 2μm-thick sputtered Al-Si-Cu film specimen section with triangle-shaped gauge marks for elongation measurement, Si springs, chucking holes and frame. The specimen has fabricated through conventional micromachining technologies. We prepared two types of Al-Si-Cu film specimens with and without thermal treatment at 623 K for an hour. Image processing was conducted to measure elongation of these specimens. During the test, the specimen section was shot using CCD camera to monitor the gap between two gauge marks until specimen failure. Elongation of the parallel section in specimen was measured directly from relative displacement of the gauge marks.The uniaxial tensile tests were conducted at room temperature (R.T.) and 358 K. For as-deposited specimen, average Young’s modulus of 63.6 GPa and yield stress of 149.8 MPa were obtained at R.T. After thermal treatment, these characteristics were measured to be 65.0 GPa and 116.8 MPa, respectively. From AFM observation, surface morphology of annealed specimen was relatively rough as compared with that of as-deposited specimen. If surface roughness is related to grain size, yield stress is thought to decrease with an increase in grain size, based on Hall-Petch law. For as-deposited specimen, average Young’s modulus of 54.2 GPa and yield stress of 121.3 MPa were obtained at 358 K. Temperature elevation provided the yield stress of as-deposited specimen with a significant drop. This is because the temperature rise during the test has yielded an annealing effect on the specimen. On the other hand, for annealed specimen, average Young’s modulus and yield stress were 55.9 GPa and 110.7 MPa, respectively, which were a little bit smaller than those at R.T. Therefore, annealing at 358 K after deposition would be significant to keep the mechanical characteristics constant if the film is employed under environments with temperature fluctuation.We are now performing the fatigue test with pulsating-tension mode using the same apparatus to investigate the fatigue life of Al-Si-Cu film specimen and to find its life acceleration factor. The specimen is subjected to cyclic loading with a constant frequency of 10 Hz at elevated temperatures. We will conduct development of the fatigue life prediction method for Al-Si-Cu film in order to estimate the lifetime of Al-Si-Cu micro-hinge structure actuated in operating RF-MEMS devices.
5:00 PM - V14.7
High Throughput In-Situ Fracture Testing of Polycrystalline Silicon.
Siddharth Hazra 1 , Maarten de Boer 1
1 Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
Show AbstractAlthough polycrystalline silicon (polysilicon) is brittle with a low fracture toughness (~1 MPa●m1/2), it is the structural material of choice in many micromachined applications. This is because of its process compatibility and its high strength (1-3 GPa), and because analysis of real devices rarely reveals fracture as a failure mode. Nonetheless, polysilicon strength remains of primary concern in MEMS reliability because of the material’s inherent flaw sensitivity and its large attendant strength distribution. For several reasons, off-chip actuators are most often applied to test the strength of polysilicon. First, they are versatile and can test many different materials. Second, they provide the high forces needed to fracture polysilicon. However, such tests can be time consuming and consequently limited test sample sizes are generally reported. Therefore, the lower limit of fracture strength is not well known, and designs in real devices tend to be conservative. In this work, we propose an in-situ mechanical system for high throughput testing of polysilicon. By cooling a thermal actuator, we achieve forces from 10 to 30 milliNewtons. To measure the strength, we directly monitor displacement of a tensile bar in-situ using a ± 1 nanometer optical Moiré metrology we have developed. This method gives a strain resolution of approximately 10-5, or a stress sensitivity of approximately 2 MPa. We have analyzed, designed and fabricated these microtest systems, and will report test data. With this approach we hope to automate fracture testing of polysilicon to test thousands of samples and therefore improve confidence in polysilicon strength values.
5:15 PM - V14.8
Barium Strontium Titanate Tuning of LTCC based Structures.
Mahmoud Al Ahmad 1 , Sandrine Payan 2 , Mario Maglione 2 , Robert Plana 1
1 , LAAS CNRS, Toulouse France, 2 , ICMCB CNRS, Bordeaux France
Show Abstract