Symposium Organizers
Kyoung-Shin Choi Purdue University
Amanda S. Barnard University of Melbourne
David J. Srolovitz Yeshiva University
Huifang Xu University of Wisconsin-Madison
V1: Metallic Nanocrystals
Session Chairs
Tuesday PM, March 25, 2008
Room 3005 (Moscone West)
9:30 AM - V1.1
Self-Assembly of Polyhedral Ag Nanoparticles for a 3-D Plasmonic Crystal.
Andrea Tao 1 , Peidong Yang 2 3
1 Institute for Collaborative Biotechnologies, UC Santa Barbara, Santa Barbara, California, United States, 2 Chemistry, UC Berkeley, Berkeley, California, United States, 3 Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractPlasmon modes supported by nanostructured noble metals facilitate the novel optical phenomena that stem from electromagnetic field enhancement, such as intense light scattering and enhanced optical transmission through sub-wavelength holes. Unlike top-down approaches, assembling metal nanocrystals with specific shapes, sizes, and spacing offers unprecedented control over the electromagnetic coupling responsible for plasmon-mediated effects. Here, shape-controlled Ag nanocrystals are self-assembled using sedimentation or evaporation-induced methods to form highly ordered three-dimensional superlattices over large volumes (~cm3). Assembly architectures are completely dictated by the differently shaped nanocrystal building blocks. The periodicity of the superlattice dictates the nature of the electromagnetic field localized around the nanocrystals, as modeled by FDTD simulations. In addition, surface plasmon modes supported by these ordered nanocrystal structures can undergo multiple scattering akin to traditional photonic crystals. Such materials may prove valuable in generating novel metamaterials for application in sub-wavelength optics, integrated photonic-plasmonic devices, and nanoscale imaging.
9:45 AM - V1.2
Hollow Gold-Silver Double Shell Nanospheres: Structure, Optical Absorption, and Surface Enhanced Raman Scattering.
Tammy Olson 1 , Adam Schwartzberg 2 , Christine Orme 3 , Chad Talley 4 , Breanna O'Connell 5 , Jin Zhang 5
1 Chemistry, University of California, Santa Cruz, California, United States, 2 , University of California at Berkeley, Berkeley, California, United States, 3 , Lawrence Livermore National Laboratory, Livermore, California, United States, 4 , Southern California Reference Laboratory, Tustin, California, United States, 5 Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, United States
Show AbstractUnique hollow gold-silver double shell nanospheres were synthesized and characterized to explore their structural properties, optical absorption, and surface enhanced Raman scattering (SERS) at the single particle level. Solid gold nanoparticles (NPs) of different sizes (48 and 35 nm) with silver shells have been synthesized and served as references for the optical and SERS properties observed for hollow gold-silver double shell nanospheres. The structures of these hollow gold-silver double shell nanospheres have been discerned using transmission electron microscopy (TEM) that reveals the uniform silver outer shell of approximately 3 nm deposited by seed mediated growth on 28 nm hollow gold nanospheres (HGNs). The growth mechanism of silver shells on HGNs and gold NPs has been determined as silver island formation before complete encapsulation. Plasmon optical absorption has been obtained using UV-Visible electronic absorption spectroscopy and it exhibits interesting and useful optical properties. Hollow gold-silver double shell nanospheres possess a plasmon band that combines those of both the silver and gold shells to expand the absorption profile in the UV-visible range, while their overall structure still maintains a spherical shape. This is useful for SERS and other applications that require spherical nanostructures and, simultaneously, broad and tunable absorption. Mercaptobenzoic acid (MBA) is used as a probe molecule to measure and compare the SERS spectra before and after a silver shell has been deposited on the HGN and solid gold NPs. The hollow gold-silver double shell nanospheres show a 4-5X enhancement over the HGNs while the solid 48 and 35 nm gold NPs with silver shell exhibited little or no SERS enhancement over their solid gold NP counterparts. Consistency of SERS spectra has been measured by evaluating the peak ratios of two ring breathing modes of MBA from single particle SERS spectra for each SERS substrate. Among the gold nanostructures, HGNs generated the most consistent SERS signal over solid gold NPs. Among the silver nanostructures, hollow gold-silver double shell nanospheres generated the most consistent SERS signal over the solid gold NPs with silver shell and solid silver NPs, although not as significant as what was sought initially. Incidentally, a change in peak ratios of the two MBA ring breathing modes is observed between the HGNs and hollow gold-silver double shell nanopsheres. The same change in peak ratios is seen for solid gold NPs and solid gold NPs with silver shell. This is attributed to the difference in binding between the sulfur to gold and silver surfaces.
10:00 AM - **V1.3
Controlled Synthesis of Gold and Silver Nanocrystals of Various Shapes.
Catherine Murphy 1
1 Dept. of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, United States
Show AbstractThe optical properties of noble metal nanoparticles depend crucially on the shape of the nanoparticle. We have developed methods to grow gold and silver nanocrystals in aqueous solution, at room temperature, that yield a plethora of shapes with well-controlled size. Recent results on the crystal growth mechanisms and surface chemistry for these materials will be presented.
10:30 AM - V1.4
Synthesis and Characterization of Gold Nanowires in Organic Solvent.
Nicolas Pazos-Perez 1 , Dmitry Baranov 1 , Michael Hilgendorff 1 , Luis Liz-Marzan 2 , Michael Giersig 1
1 Nanoparticle technology group, Center of advanced european studies and research, Bonn Germany, 2 Departamento de Quimica Fisica, Universidad de Vigo, Vigo Spain
Show Abstract10:45 AM - V1.5
Direct Growth of Metal Nanoplates on Semiconductor Substrates.
Yugang Sun 1
1 Center for Nanoscale Materials, Argonne National Laboratory, Argonne , Illinois, United States
Show AbstractShape-controlled synthesis of metal nanostructures has attracted intensive interests in the last several years because variation in morphologies of nanoparticles provides an effective means to fine tailor their properties. Various solution-phase chemical reactions have achieved great success in preparing metal nanoplates with assistance of surfactant molecules, for instance, polymeric chains (e.g., poly(vinyl pyrrolidone) or PVP, polyamine), micellar assemblies (e.g., cetyltrimethylammonium bromide or CTAB, di(2-ethyl-hexyl) sulfosuccinate or AOT), coordinating ligands, biological reagents, etc. Some of these approaches have been extended to grow metal nanostructures with well-defined shapes on solid substrates. For example, seed-mediated synthetic processes with assistance of surfactants can grow gold nanorods on silicon or glass substrates and gold nanoplates on conductive indium tin oxide substrates. However, the use of surfactant molecules for directing the anisotropic growth of metal nanoparticles, somehow, complicates the reaction systems and contaminates the surfaces of metal nanoparticles. Most recently, Buriak and coworkers study the growth of metal nanostructures with specific shapes (e.g., nano-inukshuks) on semiconductor substrates. In this presentation, we report a simple and surfactant-free approach to fast growing pristine metal nanoplates with well-controlled thicknesses and edge lengths on semiconductor wafers through galvanic reactions between pure aqueous solution of metal salts and n-type semiconductor substrates. Figure 1 shows an SEM image of silver nanoplates with thickness of ~28 nm and edge lengths of 400-450 nm grown on an n-type (110) GaAs wafer. All of the as-grown metal nanoplates stand out of the surface of the semiconductor substrates and have uniform thickness which can be tuned in the range from ~20 to 150 nm by controlling reaction conditions. In addition, the surfaces of the metal nanoplates are chemically clean due to the absence of surfactant molecules. The as-grown metal nanoplates as well as the hybrid metal/semiconductor systems mat find applications in unique photophyical and photochemical processes, such as photocatalysis and photoelectrochemistry. This work has been supported by Department of Energy, Office of Science, Office of Basic Energy Sciences under contract No. DE-AC02-06CH11357.
11:30 AM - V1.6
Continuous Redshifts of Surface Plasmon Resonance in Ordered Au Nanodisk Arrays via Chemical Etching.
Yue Bing Zheng 1 , Wei Yan 1 , Thomas R. Walker 1 , Tony Jun Huang 1
1 Engineering Science and Mechanics, Pennsylvania State University, University Park , Pennsylvania, United States
Show AbstractContinuous redshifts of localized surface plasmon resonance (LSPR) was achieved in ordered Au nanodisk arrays by chemical etching method. The nanodisk arrays were fabricated on glass substrates using nanosphere lithography (NSL) combined with two steps of reactive ion etching (RIE). Real-time spectrometric investigations showed that a continuous redshift up to 200 nm could be obtained by chemically etching the Au nanodisks. The long-range redshifts spanned the LSPR of Au nanodisks from visible light region into the near-infrared. Atomic force microscopy (AFM) studies attributed the redshifts to the layer-by-layer etching process that increased the diameter-to-thickness ratio of the Au nanodisks. The topology-dependent redshifts were further confirmed by discrete dipole approximation (DDA) calculations. As comparisons, only slight blueshifts were observed in the chemical etching of Au nanosphere arrays and Au nanosphere colloids. The blueshifts arose from the shrinkage of size of nanospheres and agreed with calculations based Mie theory. The long-range redshifts of LSPR, combined with NSL-based low-cost and high-throughput nanofabrication, and simple chemical etching method, will enable applications of Au nanodisk arrays in many different fields with specific requirements on the LSPR peak positions, such as surface-enhanced Raman spectroscopy (SERS), label-free biosensing, imaging, and plasmonic integrated circuits.
11:45 AM - V1.7
Soft-Template Synthesis of Platinum Nanocoins Using Bicelles.
Yujiang Song 1 , Rachel Dorin 1 2 , Robert Garcia 1 2 , Sivakumar Challa 1 2 , Frank van Swol 1 2 , John Shelnutt 1 3
1 Nanomaterials Sciences Department, Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 Chemical & Nuclear Engineering Department, The University of New Mexico, Albuquerque, New Mexico, United States, 3 Department of Chemistry, University of Georgia, Athens, Georgia, United States
Show Abstract12:00 PM - **V1.8
Shape Control and Optical Properties of Silver and Gold Nanoparticles.
George Schatz 1
1 Chemistry, Northwestern University, Evanston, Illinois, United States
Show AbstractIn this paper I describe a number of examples where the ability to control the shape and size of silver and gold nanoparticles leads to unique optical properties(both for extinction and Raman scattering). Included is an update on the current status of the wet chemical synthesis of silver triangular nanoprisms, as originally developed by Mirkin, where plasmon mediated growth produces prisms whose edge length is determined by the wavelength of the light that is used to stimulate growth. Another example (also a collaboration with Mirkin) refers to gold nanorod structures that are made using a technique called On-Wire-Lithography (OWL), and a third example (collaboration with Teri Odom) refers to gold pyramids that are made using soft lithography.
12:30 PM - V1.9
Structure of the Silver-Gold Core-Shell Nanoparticles.
Shaomin Wu 1 , Domingo Ferrer 2 , Miguel Jose-Yacaman 2
1 Texas Materials Institute, The University of Texas at Austin, Austin, Texas, United States, 2 Department of Physics and Astronomy , The University of Texas at San Antonio, San Antonio, Texas, United States
Show Abstract12:45 PM - V1.10
Formation of Pd/Au Nanostructures from Pd Nanowires via Galvanic Replacement Reaction.
Xiaowei Teng 1 , Weiqiang Han 1 , Qi Wang 2 , Anatoly Frenkel 2 , Jose Rodriguez 3 , Wen Wen 3 , Ping Liu 1 3 , Jonathan Hanson 3
1 Center for Functional Nanomaterials, Brookhaven National Lab, Upton, New York, United States, 2 Department of Physics, Yeshiva University, New York, New York, United States, 3 Department of Chemistry, Brookhaven National Lab, Upton, New York, United States
Show AbstractNoble metals and their alloys, palladium and gold in particular, have been used in various technologically important areas for many years. The alloy of palladium and gold has shown various catalytic activities towards phosphoric acid fuel cell, CO/H2 oxidation, oxidation of alcohols to aldehydes, and production of vinyl acetate monomers. Since the performance of bimetallic nanoclusters is associated with their structural diversities to a great extent, detailed studies of various two–metal structures, such as intermetalic alloy (two metal atoms are mixed with definite proportions), random alloy (two metal atoms are mixed statistically in accordance with the overall concentration), non–random alloy (one metal is core rich, while the other is shell rich) or phase segregation (two metals are in separated phases), are essential for their applications. Here we present a mechanistic study on the galvanic replacement reaction between Pd ultrathin nanowires (2.4 + 0.2 nm in width, over 30 nm in length) and AuCl3 in toluene. We monitored both morphological and structural changes during the reaction for up to 10 hours. On the basis of the morphological evolution, we proposed oxidative etching from Au cation was responsible for the breakdown of Pd nanowires and consequent Ostwald Ripening would account for the morphology changing from one dimension nanostructure to nearly spherical nanoparticles. By using combined techniques such as high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), energy dispersive X–ray spectrometry (EDS) and extended X-ray absorption fine structure (EXAFS) spectroscopy, we found that a supervising phase transition from non–random Pd68Au32 alloy (Au and Pd atoms predominantly segregated at the core/shell, respectively) to random Pd45Au55 alloy (uniformly mixed Pd and Au atom inside the nanoparticles).
V3: Poster Session I
Session Chairs
Wednesday AM, March 26, 2008
Salon Level (Marriott)
9:00 PM - V3.11
Cubic Nanoassemblies Comprising Octahedral CeO2 Nanocrystals.
Seiichi Takami 1 , Satoshi Ohara 2 , Tadafumi Adschiri 3 , Yutaka Wakayama 1 , Toyohiro Chikyow 1
1 Advanced Electronic Materials Center, National Institute for Materials Science, Tsukuba, Ibaraki, Japan, 2 Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka, Japan, 3 Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi, Japan
Show Abstract9:00 PM - V3.12
Impact of Low Kink Density and Weak Step Fluctuations on Calcite Growth and Interaction with Shape-modifying Peptides.
Raymond Friddle 1 , S. Roger Qiu 1 , Alexander Chernov 1 , Luis Zepeda-Ruiz 1 , George Gilmer 1 , Patricia Dove 2 , James De Yoreo 1
1 Chemistry, Materials, Earth and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California, United States, 2 Department of Chemistry, Virginia Tech, Blacksburg, Virginia, United States
Show Abstract9:00 PM - V3.13
Facile Electrochemical Synthesis of Single-crystalline Copper Nanospheres, Pyramid and Triangular Nanoplates from Lithia-cuprous Oxide Composite Thin Films.
Yan Yu 1 , Chunlei Wang 1 , Chun Chen 1
1 , Florida International University, Miami,, Florida, United States
Show Abstract9:00 PM - V3.16
Effect of Alloy Composition on Diversity in Crystal Shapes of III-Nitride Nanostructures Grown on Different Crystallographic Planes by MOCVD.
Vibhu Jindal 1 , James Grandusky 1 , Neeraj Tripathi 1 , Mihir Tungare 1 , Fatemeh Shahedipour-Sandvik 1
1 College of Nanoscale Science and Engineering, University at Albany- SUNY, Albany, New York, United States
Show Abstract9:00 PM - V3.17
Computational Models for Catalyzed Growth of Si Nanowire.
Seunghwa Ryu 1 , Wei Cai 2
1 Physics, Stanford University, Stanford, California, United States, 2 Mechanical Engineering, Stanford University, Stanford, California, United States
Show AbstractWe present molecular simulation models for the growth of silicon nanowires from gold catalyst particles. Because the number of atoms involve in this process is above 1000, it is infeasible to use ab initio models. Hence our first step is to develop an interatomic potential model for Au-Si using the modified embedded-atoms method (MEAM) framework. For the first time, we computed the Au-Si phase diagram entirely from the interatomic potential. The melting points are computed from free energy methods with uncertainties less than 1K. Molecular simulations of the interaction between the gold nanoparticle with the Si substrate and Si NW is presented.
9:00 PM - V3.18
Growth of Crystalline Lanthanum Hexaboride and Neodymium Hexaboride Nanoobelisks and Nanowires.
Joseph Brewer 1 , Gonghua Wang 1 , Morris Wang 3 , Chin Li Cheung 1 2
1 Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, United States, 3 , Lawrence Livermore National Laboratory, Livermore, California, United States, 2 Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska, United States
Show AbstractThe advancement of vacuum nanoelectronics depends on the development of efficient electron emitters at the nanoscale and their electron emission properties. Low work function and high aspect ratio of materials have been widely established as among the most significant factors that can effectively lower the applied field emission voltage – and thus the efficiency – of field emission devices. Lanthanum hexaboride (LaB6) and neodymium hexaboride (NdB6) are among the materials with the lowest known work function (2.6 eV and 1.6 eV, respectively). While the synthesis of different lanthanide nanowires has been reported in literature, the shape control synthesis of robust LaB6 and NdB6 nanostructures are lacking. Herein, we report our development of a catalyst-assisted chemical vapor deposition process for the growth of single-crystalline LaB6 and NdB6 nanoobelisks and nanowires. Growth of these obelisks and wires was controlled by the substrate lattice orientation, flux of reactants, catalyst particles, and the temperature of the reaction. The nano-obelisk tips have diameters ranging from 5 to 50 nm. The diameters of nanowires range from 20 to 100 nm, These nanostructures have preferred (100) growth orientations. The shape effect of these nanostructures on their field emission properties will also be discussed.
9:00 PM - V3.2
3-Dimensional Structure of Metallic Nanoparticles Using High Energy X-Ray Diffraction and Reverse Monte Carlo Simulations.
Nicholas Bedford 2 1 , Valeri Petkov 2
2 Physics, Central Michigan University, Mt. Pleasant, MI, Michigan, United States, 1 Materials Engineering, University of Cincinnati, Cincinnati, Ohio, United States
Show AbstractFor years, x-ray diffraction (XRD) has been the tool of choice for determining atomic structures for materials. Classically this could only be done on materials exhibiting long range periodic order and, to an extent, semi-crystalline materials. A fairly new method of analyzing more disorder materials is atomic pair distribution function (PDF) analysis. The PDF method has been successfully used to determine structures with varying degrees of crystalline order and long range periodicity, including various types of nanostructures. Often this is done by refining experimental and structural parameters based off symmetries and space groups present in the bulk material. However, once a nanostructured material reaches sizes below 2-3 nm its starts to deviate greatly from the bulk counterpart, making this type of traditional analysis difficult, if not impossible. Here the authors use reverse Monte Carlo (RMC), a structure simulation method generally associated with continuous disorder materials (such as glasses and liquids), to guide the structure determination in these discrete nanoparticle systems. Examples presented here are ruthenium, gold, and platinum nanoparticles which all have useful catalytic properties.
9:00 PM - V3.20
Enhancement of the Photoelectrochemical Properties of Electrochemically Grown Dendritic Cuprous Oxide Films.
Colleen McShane 1 , Matthew Siegfried 1 , Kyoung-Shin Choi 1
1 Chemistry, Purdue University, West Lafayette, Indiana, United States
Show AbstractCuprous oxide is an affordable, non-toxic material useful for solar energy conversion due to its relatively low band gap energy (Eg = 2eV) that allows for the utilization of visible light. When producing cuprous oxide as a film-type electrode, controlling its interfacial morphology is important to enhance desired physical and chemical properties. In that context, stabilizing dendritic growth (i.e. diffusion-limited growth) of cuprous oxide can be highly advantageous because it allows for facile surface coverage and an increase in surface reactivity and surface area. In this presentation, we report electrochemical conditions that allow for the dendritic growth of cuprous oxide to form film-type electrodes. Typically, dendritic growth via electrodeposition can be stabilized when a high overpotential is applied to increase the deposition rate above the diffusion rate. This creates a depletion layer around the growing surface and the growth becomes limited by diffusion, allowing branching growth to occur. However, dendritic growth of Cu2O has not been easily achieved because applying the higher overpotentials necessary for the dendritic growth of Cu2O often results in the co-deposition of Cu metal. Even if the initial applied potential was chosen to produce pure Cu2O, the pH drop accompanying the production of Cu2O (2Cu2+ + H2O + 2e- → Cu2O + 2H+) would trigger the deposition of Cu metal during Cu2O deposition (the formation of Cu is more feasible at lower pH). Conditions to avoid this problem and produce pure dendritic cuprous oxide films will be discussed in this presentation. Chemical and electrochemical conditions to tune the fine details of dendritic growth (e.g. nucleation density, degree of branching) will also be discussed. Finally, the effect of dendritic morphology on photoelectrochemical properties will be presented.
9:00 PM - V3.21
Shape- and Size-Controlled Synthesis of Platinum Nanostructures Using Various Surfactant Assemblies with/without Incorporated Photocatalysts.
Yujiang Song 1 , Robert Garcia 1 2 , Rachel Dorin 1 2 , Haorong Wang 1 2 , Sivakumar Challa 1 2 , Yan Qiu 1 2 , Craig Medforth 1 2 , Frank van Swol 1 2 , James Miller 1 , John Shelnutt 1 3
1 Nanomaterials Sciences Department, Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 Chemical & Nuclear Engineering Department, The University of New Mexico, Albuquerque, New Mexico, United States, 3 Department of Chemistry, University of Georgia, Athens, Georgia, United States
Show Abstract9:00 PM - V3.23
Size and Habit Evolution of PETN Crystals – A Lattice Monte Carlo Study.
Luis Zepeda-Ruiz 1 , George Gilmer 1 , Amitesh Maiti 1 , Richard Gee 1
1 Chemistry, Materials & Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States
Show Abstract9:00 PM - V3.25
Morphological Stability of Epitaxial Core-shell Nanowires.
Moneesh Upmanyu 1 2 , Hailong Wang 1
1 Engineering Division, Materials Science Program, Colorado School of Mines, Golden, Colorado, United States, 2 Bioengineering and Life Sciences Program, Colorado School of Mines, Golden, Colorado, United States
Show Abstract9:00 PM - V3.26
Shape Deformation of Colloidal Titania Nanoparticles by Means of Ion Irradiation.
Juan-Carlos Cheang-Wong 1 , Ana-Lilia Diaz-Fonseca 1
1 Instituto de Fisica, UNAM, Experimental Physics Department, Universidad Nacional Autonoma de Mexico, Mexico, D.F., D.F., Mexico
Show Abstract9:00 PM - V3.27
Chemical Transformation from Binary to Ternary Nanocrystals by a Cation Redox Reaction and Their Application in Fuel Cell.
Chia-Chun Chen 1 , Di-Yan Wang 1 , Ching-Hsiang Chen 3 , Bing-Joe Hwang 2
1 Department of Chemistry, National Taiwan Normal UniVersity, Taipei Taiwan, 3 , Institute of Atomic and Molecular Sciences, Academia Sinica,, Taipei Taiwan, 2 Chemical Engineering, National Taiwan UniVersity of Science and Technology, Taipei Taiwan
Show Abstract9:00 PM - V3.28
Design of Nanoscaled Architectures of Manganese Oxides by Soft Chemistry in Aqueous Medium. Towards Enhanced Materials for Lithium Battery Electrodes.
David Portehault 1 , Sophie Cassaignon 1 , Emmanuel Baudrin 2 , Jean-Pierre Jolivet 1
1 Laboratoire Chimie de la Matière Condensée de Paris, Université Pierre et Marie Curie-Paris6 - CNRS UMR 7574, Paris France, 2 Laboratoire de Réactivité et Chimie des Solides, Université Picardie Jules Vernes - CNRS UMR 6007, Amiens France
Show Abstract9:00 PM - V3.29
Growth and Optical Properties of SnO2 Ultra-small Nanorods by the Novel Micelle Techniques.
Satchidananda Rath 1 , S. Nozaki 1 , H. Ono 1 , K. Uchida 1 , S. Kojima 2
1 Electronic Engineering, The University of Electrocommunication, Tokyo Japan, 2 Applied Physics and Chemistry, The University of Electrocommunication, Tokyo Japan
Show AbstractAmong the oxide semiconductors, tin dioxide (SnO2), which possesses unique electrical and optical properties, has been regarded as a technologically important material and can be applied to solar cells, transparent conducting electrodes, gas sensors and more. In recent years, considerable efforts have been made to fabricate various forms of nanostructured SnO2 using both the chemical and physical deposition techniques to observe their distinct quantum bounded and surface dominated electrical and optical properties. However, most of the techniques yield coarse and irregular-shaped SnO2 nanostructures with the size much larger than the Bohr radius, aB = 2.7 nm, too large to observe the significant quantum confinement effects (QCE). Although, the micelle growth have taken advantage over the categories of the bottom up approaches because of the predetermined micro-structural micelle geometry, the reverse micelles technique is most abundantly used to synthesize mere nanoparticles of various materials, including metals, oxides, hydroxides and some inorganic compounds. We have modified the micelle geometry by replacing the oil by alcohol, which makes the technique novel for the growth of ultra-small nanorods and is uncommon by the traditional micelle technique. By controlling the temperature and concentration of the surfactant, we have successfully fabricated ultra-small SnO2 nanorods with dimension well within the quantum regime using the ternary water-surfactant-alcohol micelle (WSAM) growth technique. The micelles contained 0.05 M Sn(CH3COO)4 solution, 0.2 M cytriltrimethylammonium bromide (CTAB) as a surfactant and 10 % alcohol (e.g., methanol, ethanol or butanol). The temperature was set to 400 K. As observed from the transmission electron microscopy, the average diameter and length of the SnO2 nanorods were found to be 1 nm and 3 nm, respectively. The x-ray diffraction patterns obtained by grazing-angle x-ray diffraction evidenced the tetragonal phase of the SnO2 with the lattice parameters, a = 4.76 Å and c = 3.19 Å, which were slightly different from those in bulk (a = 4.738 Å and c = 3.187 Å). The optical absorption spectra of the nanorods showed a blue shift of optical bandgap to 4.78 eV from that of bulk counter part (3.6 eV). The photoluminescence spectrum peaks are at 3.72, and 3.47, 3.29, 2.83 and 2.63 eV. They were lower than the optical bandgap and were attributed to defects in the SnO2 nanorods. In summary, we successfully made SnO2 nanorods with good crystallinity by the novel micelle technique, which is different from the conventional reverse micelle technique.
9:00 PM - V3.3
Controlling Length of Gold Nanowires with Large-Scale : X-ray Absorption Spectroscopy Approaches to the Growth Process.
Hao Ming Chen 1 , Ru-Shi Liu 1
1 Department of chemistry, National Taiwan University , Taipei Taiwan
Show AbstractSince most chemical reactions take place in solution. Reactive intermediates also are, by definition, difficult or impossible to crystallize. In order to accurately follow the reaction, it is essential to confirm that the crystallographic structure accurately represents the molecule of interest when it is in solution. One promising way to achieve this goal involves using X-ray absorption spectroscopy (XAS) here especially for solution phase. The present work has clearly established that gold ions evolved from Au-Cl complex, to Au rods through the reaction in seed-mediated growth method. The theoretical simulation of X-ray absorption spectra further revealed that evolution of gold, ultra-fine small clusters (Au13) presented after reducing agent (ascorbic acid) was added to growth solution. XAS results allow approaches the growth of gold and guide a proper scheme about the growth process. A redesigned seed-assisted growth method, a serial addition of growth solution, was employed to achieve the goal of the consecutive support of gold. The development approach was found to successfully fabricate 1-D gold nano rods/wires with a tunable size from 50 nm to 1.7 μm.
9:00 PM - V3.5
Kinetically Probing Site-Specific Heterogeneous Nucleation and Hierarchical Growth of Nanobranches.
Roland Njabon 1 , Z. Tian 1 , Vijay Varadan 2
1 Chemistry, University of Arkansas-Fayetteville, Fayetteville, Arkansas, United States, 2 Microelectronics and Photonics, University of Arkansas-Fayetteville, Fayetteville, Arkansas, United States
Show Abstract9:00 PM - V3.6
Thermal-assisted Photoreduction of Silver Nanowires.
Hsien-Tse Tung 1 , Cheng-Wei Yen 1 , Jenn-Ming Song 2 , In-Gann Chen 1
1 Materials Science and Engineering, National Cheng-Kung University, Tainan Taiwan, 2 Materials Science and Engineering, National Dong Hwa University, Hualien Taiwan
Show Abstract9:00 PM - V3.7
Transformation of Se-based Nanostructured Materials.
Geon Dae Moon 1 , Unyoung Jeong 1
1 Metallurgical Engineering, Yonsei Univ., Seoul Korea (the Republic of)
Show AbstractSelenium is an interesting material due to its electronic and photonic properties enabling a range of applications such as photocopying machine, pressure sensor, and electrical rectifier. Of all characteristic properties, the high reactivity with chemical reagents can make selenium transform into other functional materials. So far, it has been reported that Se can transform into Se@Pt by physical coating and Se@Ag2Se with silver precursor, further followed by CdSe, PbSe, and ZnSe by ion exchange. Spherical Se colloids as a starting material can be applied to synthesize trigonal selenium nanowires. The transformed structures from Se colloids can be used to obtain unconventional nanostructures by utilizing the high solubility of Se in various solvents. In this talk, we will provide a number of ways to fabricate these Se-based nanostructured materials and their transformation into other types of structures.
9:00 PM - V3.8
Controlled Growth and Particle Size Control of 2D Cationic Materials for Enhanced Catalytic Properties.
Harris Shaikh 1 , Claudia Swanson 1 , Dave Rogow 1 , Marc Bresler 1 , Allen Oliver 1 , Scott Oliver 1
1 Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, United States
Show Abstract9:00 PM - V3.9
Growth of t-Se Nanowires in Polymer Thin Films and Fabrication of 2-D Nanowire Networks with Chemical Junctions.
Sungwook Ko 1 , Geon Dae Moon 1 , Seong Won Lee 1 , Unyong Jeong 1
1 , yonsei university, 134 shinchon-dong, seodaemoon-gu Seoul Korea (the Republic of)
Show Abstract
Symposium Organizers
Kyoung-Shin Choi Purdue University
Amanda S. Barnard University of Melbourne
David J. Srolovitz Yeshiva University
Huifang Xu University of Wisconsin-Madison
V6: New Methods to Grow and Study Crystals
Session Chairs
Thursday AM, March 27, 2008
Room 3005 (Moscone West)
9:30 AM - V6.1
Binary Nanorod Heterostructures Synthesized by Partial Cation Exchange.
Bryce Sadtler 1 , Steven Hughes 1 , Richard Robinson 2 , A. Alivisatos 1 2
1 Department of Chemistry, University of California, Berkeley, Berkeley, California, United States, 2 Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractPartial cation exchange is a novel route to synthesize nanocrystal heterostructures, consisting of two materials epitaxially connected within an individual nanocrystal. This single-step, chemical transformation enables the systematic tuning of the composition and properties of colloidal semiconductor nanocrystals. Upon the addition of copper or silver salts to a colloidal solution of cadmium sulfide (CdS) nanorods, the spontaneous replacement of cadmium cations within the CdS lattice for copper (silver) cations occurs, while preserving the original dimensions of the nanorods. The exchange process produces crystalline regions of copper sulfide (silver sulfide) within the CdS nanorods, creating binary nanorod heterostructures. The morphology of the heterostructures depends on the cation species used and the fraction of the nanorod converted. High-resolution transmission electron microscopy of the binary nanorods shows that the crystal lattices are epitaxially connected at their interface. This well-defined contact leads to strong electronic coupling between the materials, evidenced by fluorescence spectroscopy. The absorption and emission of light of the binary nanorods can be tuned throughout the visible and near-infrared regions making these novel nano-scale architectures interesting for a variety of optoelectronic applications including near-infrared emission and solar energy conversion.
9:45 AM - V6.2
Correlated Single Particle Spectroscopy and SEM Imaging of Gold Nanodecahedra.
Jessica Rodriguez-Fernandez 1 2 , Ana Sanchez-Iglesias 1 , Carolina Novo 2 , Alison Funston 2 , Isabel Pastoriza-Santos 1 , Luis Liz-Marzan 1 , Paul Mulvaney 2
1 Química Física and Unidad Asociada CSIC, Universidade de Vigo, Vigo, Pontevedra, Spain, 2 School of Chemistry & Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
Show Abstract10:00 AM - **V6.3
Quantifying Shape Evolution in Nanomaterials.
Christine Orme 1 , Jeremy Gray 1 , Danxu Du 3 , Kyoung-Shin Choi 2 , David Srolovitz 4
1 , Lawrence Livermore National Lab, Livermore, California, United States, 3 , Princeton University, Princeton, New Jersey, United States, 2 , Purdue University, West Lafayette, Indiana, United States, 4 , Yeshiva University, New York, New York, United States
Show Abstract10:30 AM - V6.4
Engineering the Properties of Wurtzite Zinc Oxide via Sonochemical and Hydrothermal Shape-controlled Synthesis.
Marco Palumbo 1 , Simon Henley 1 , Thierry Lutz 1 , Vlad Stolojan 1 , S. Ravi P. Silva 1
1 Faculty of Engineering & Physical Sciences, Nano-Electronics Centre, Advanced Technology Institute, Guilford United Kingdom
Show Abstract10:45 AM - V6.5
Carbon-induced Strain Engineering for Size and Density Control of Self-assembled Germanium Quantum Dots.
Sung Won Hwang 1 , Sung Kim 1 , Seung Hui Hong 1 , Jun Woo Park 1 , Hosun Lee 1 , Suk-Ho Choi 1 , Wondong Kim 2 , Ja Yong Koo 2
1 College of Electronics and Information, Kyung Hee University, Yongin, Kyungkido, Korea (the Republic of), 2 The Center for Atomic Control of Heteroepitaxy Group, Korea Research Institute of Standards and Science, Daejeon Korea (the Republic of)
Show Abstract11:30 AM - V6.6
Kinetic- or Thermodynamic-Growth Formation of Pd Nanocrystals: a combined TEM-DLS Approach.
Gilles Berhault 1 , Marta Bausach 1
1 IRCELYON, University Lyon I, Villeurbanne France
Show AbstractPalladium nanoparticles (NPs) with defined morphologies were successfully synthesized using a seed-mediated approach in the presence of CTAB (cetyltrimethylammonium bromide). Various types of morphologies were obtained going from isotropic cubes and icosahedral particles to nanorods or bipyramids.A systematic study of experimental conditions showed that the morphology was mainly governed by the crystal growth rate. The CTAB surfactant controls the rate of reduction of the Pd precursor by embedding it inside micelles leading to a kinetic-controlled regime and a preferential formation of nanorods (NRs). Shifting the conditions to a thermodynamic-controlled regime selectively led to the formation of cubic (80%) or icosahedral (100%) particles. Cubes were formed by avoiding the embedding of Pd while icosahedral particles were obtained by capping the Pd seeds with citrate. To gain insight into the growth mechanism, the synthesis of the Pd nanocrystals was also followed combining TEM and DLS (dynamic light scattering). DLS was used to determine the average growth rate of the Pd particles with time. The growth rate was correlated to NP’s shape distribution determined by TEM analysis. Attention was paid to the influence of the seed aging and concentration. DLS was a technique of choice to in situ follow the growth kinetics from the injection of the Pd seeds to the final morphology. Using DLS combined with TEM, several important conclusions were obtained about the growth mechanism. An increase of the amount of seeds injected into the growing solution led to higher particle growth rate for short synthesis time (up to ~10-15 min). This result is consistent with a particle growth governed by the frequency of collisions between the growing NPs and monomers. A higher amount of seeds also promotes the formation of NRs at the expense of cubes and icosahedra. Higher flux of monomers favored the formation of anisotropic particles. Our results thus show a good correlation between the kinetic data and the NP shape distribution.Conversely, the seed size did not influence the growth kinetics. This is also coherent with a particle growth rate governed by the frequency of collision between growing NPs and monomers. However, seed aging exerts an effect on the NP shape. This effect is attributed to a change in the morphology of the seeds with aging. The morphology of seeds could then be regarded as a directing-shape parameter.
11:45 AM - V6.7
Calcite Nano-fibers and Nano-architectures Produced by Micro-organisms in Soil Environments.
Huifang Xu 1 , Tianhu Chen 1 2
1 Materials Science Program, and Geology & Geophysics, University of Wisconsin, Madison, Wisconsin, United States, 2 School of Natural Resources and Environmental Engineering, Hefei University of Technology, Hefei, Anhaui, China
Show AbstractThursday, March 27Transfer Poster V3.22 to V6.7 @ 10:45 AMCalcite Nano-fibers and Nano-architectures Produced by Micro-organisms in Soil Environments. Huifang Xu
12:00 PM - **V6.8
Quantitative 3D Measurement of Size, Shape and Distribution by Electron Tomography.
Paul Midgley 1 , Edmund Ward 1 , Juan-Carlos Hernandez 1 , Ana Hungria 1
1 Department of Materials Science, University of Cambridge, Cambridge United Kingdom
Show AbstractThe shape, size and distribution of structures is of paramount importance within many modern devices and materials. These parameters may dictate the overall property of a device, or the activity of a functional material, and many structures will have critical features at the nanometre scale and in three dimensions. It is of course important to be able to correlate any variations in property with changes to composition and structure. Imaging techniques, based on electron tomography, have been developed to enable 3D reconstructions of structurally complex objects with nanometre resolution. To be of value, such reconstructions should be quantitative and offer the possibility of true 3D metrology at the nanoscale. In recent years, electron tomography, and especially tomography based on scanning transmission electron microscopy high angle annular dark-field (STEM HAADF) imaging, has developed rapidly in the materials science community to provide accurate 3D reconstructions with minimal artefacts. In this paper we show how this technique can be applied to a number of nanoscale systems to elucidate the 3D morphology quantitatively and with accuracy. In particular, we focus on the determination of the porosity and surface morphology of mesoporous silica, used for heterogeneous catalysis, how faceting can be elucidated in nanoscale crystals (both natural and man-made) and also how new techniques, such as dual-axis tomography and on-axis tomography, in which the sample may be rotated a full 360 degrees, coupled with new iterative algorithms, can enhance the information content and overall fidelity of electron tomographic reconstructions.
12:30 PM - V6.9
Direct Imaging Individual Atoms within Three-Layer Au/Pd Nanoparticles.
Domingo Ferrer 1 , Doug Blom 2 , Lawrence Allard 2 , Sergio Sergio Mejia 3 , Miguel Jose-Yacaman 1
1 Chemical Engineering, The University of Texas at Austin, Austin, Texas, United States, 2 Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States, 3 Facultad de Ciencias Físico Matemáticas, Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
Show Abstract12:45 PM - V6.10
Nanocrystal Synthesis: from Molecular to Supramolecular Chemistry.
Y. Charles Cao 1
1 Chemistry, University of Florida, Gainesville, Florida, United States
Show AbstractNanoscience is recognized as one of the most exciting frontiers in modern science. This excitement stems from the impact nanoscience is having in both basic science and technology development. In the basic science arena, we are discovering that all materials exhibit new and interesting properties when the particles composing this material approach nanoscopic dimensions. On the technological side, nanoscience has the possibility of profoundly impacting technologies that run the gamut from medical diagnostics to integrated circuits. Inorganic nanocrystals, which are often described as “artificial atoms,” are among the most important classes of building blocks in nanoscience and nanotechnology. This talk will discuss the fundamental principles behind the synthesis of high-quality nanocrystals. In addition, we will show that these principles can be used to control nanocrystal assembly through a supramolecular synthesis, which has resulted in a new type of well-defined colloidal superparticle (i.e., supercrystalline collection of artificial atoms in the form of colloidal particle). The ability to control nanocrystal synthesis and assembly will open a rational way to fabricate functional materials of interest for applications such as biomedical diagnosis, catalysis, plasmonics, and high-density data storage.
V8: Poster Session II
Session Chairs
Friday AM, March 28, 2008
Salon Level (Marriott)
9:00 PM - V8.1
Atomistic Study of Synthesis of Bimetallic Clusters by Coalescence of Two Metallic Clusters.
S. Mizuno 1 , K. Shintani 1
1 Department of Mechanical Engineering and Intelligent Systems, University of Electro-Communications, Chofu, Tokyo, Japan
Show AbstractMetallic clusters show excellent performance as catalysts because of their high surface-to-volume ratio. An inert-gas aggregation source is an experimental method by which clusters are produced. In such a method, cluster coalescence is one of growth modes of clusters. Bimetallic clusters also attract much attention of researchers because of their novel physical and chemical properties. At coalescence of two metallic clusters of different species, alloying or core-shell structuring tends to occur spontaneously. Resulting alloyed clusters or core-shell clusters will behave as unique catalysts. In this paper, morphological evolution of two metallic clusters of different elements at coalescence is investigated using molecular-dynamics simulation. All pair combinations of the elements Au, Ag, Pt, and Pd are considered. The interactions between such metallic atoms are calculated by using generic embedded-atom method (GEAM) potential. Two clusters of icosahedral structure are equilibrated at specified temperature beforehand. The two clusters are put close to each other, where the nearest two atoms belonging to the two clusters, respectively, start to interact with each other. After coalescence the original surfaces of the two clusters decrease, and the surface energy is transformed into the kinetic energy. Consequently, the temperature of the united cluster rises. If this temperature is higher than the melting temperature, melting and local alloying at the interface occur. If alloying spreads into the united cluster, an alloyed bimetallic cluster is synthesized. If melting occurs only in one of the two clusters, and the atoms in liquid phase gradually cover the surface of the other cluster, a core-shell cluster appears. The morphological evolutions in the two modes of coalescence are followed, and under what conditions each mode of coalescence occurs is discussed. The results show that the surface energy and atom size of two clusters determine which mode is selected at coalescence.
9:00 PM - V8.10
Shape and Size Control of Ni/NiO Core/Shell Nanostructures.
Nitin Chopra 1 , Leslie Claypoole 2 , Leonidas Bachas 1
1 Chemistry, University of Kentucky, Lexington, Kentucky, United States, 2 Chemistry, Fairmont State University, Fairmont, West Virginia, United States
Show Abstract9:00 PM - V8.11
From TiCl3 to Nanoparticles of TiO2 (Anatase, Brookite or Rutile): Soft Conditions for Precipitation of Original Shaped Particles.
Sophie Cassaignon 1 , Magali Koelsch 1 , Jean-Pierre Jolivet 1
1 Laboratoire Chimie de la Matière Condensée de Paris, Université Pierre et Marie Curie-Paris6 - CNRS UMR 7574, Paris France
Show Abstract9:00 PM - V8.13
Morphological Evolution of Electrodeposited Nanocrystalline Al-Mg Alloy Powders.
Sankara Sarma Tatiparti 1 , Mahesh Tanniru 1 , Fereshteh Ebrahimi 1
1 Materials Science and Engineering, University of Florida, Gainesville, Florida, United States
Show AbstractAl-Mg alloy powders were fabricated using electrodeposition technique. The composition of deposits was varied from Al-rich (~95 at.%) to Mg-rich (~95 at.%) by adjusting the deposition parameters. The alloys were made in the mass transport regime which resulted in dendritic growth in most deposits. The XRD analysis showed that deposits crystallized as supersaturated fcc-Al and/or hcp-Mg phases. Due to the non-equilibrium deposition conditions used in this study the formation of equilibrium intermetallic phases was avoided except in the deposit with the highest Mg content. The Al-rich alloy (<10 at.%Mg) crystallized in the form of large single crystals with octahedral shape, suggesting the development of {111} facets. As the amount of Mg in Al solid solution was increased (10 to 20 at.%Mg) rod-like and feather-like morphologies developed. At higher Mg contents a globular morphology with “smooth” and “rough” surface texture was found. The rough globules always formed over the smooth ones. Detailed observations revealed that some dendrites were initially formed with rod-like or feather-like morphology and upon further growth evolved into the globular morphology. When the composition of the alloy was close to pure Mg (~5 at.%Al) similar to the Al-rich alloy, large faceted crystals were observed.SEM, EPMA and TEM studies of dendrites revealed that the rough globules were composed of nano-size hcp-Mg crystals and all other morphologies were made of Al-rich fcc phase. TEM results showed that the smooth globules were composed of a shell of very fine Al-rich nanocrystals with a core of coarser crystals. Also, the feather-like dendrites with a lower Mg content were made of nanocrystalline structure. Both fcc-Al and hcp-Mg nanocrystalline phases were found to be highly porous with pore sizes in the nano-regime. In this talk the evolution of different morphologies will be discussed in terms of composition, grain size and deposition conditions. The financial support by NSF (Grant DMR-0605406) is greatly appreciated.
9:00 PM - V8.14
Density Functional Calculations for Diffusion Path-way and Energy Barriers Determination of Precursor Adatoms on Different Crystallographic Planes of GaN.
Vibhu Jindal 1 , James Grandusky 1 , Neeraj Tripathi 1 , Mihir Tungare 1 , Fatemeh Shahedipour-Sandvik 1
1 College of Nanoscale Science and Engineering, University at Albany- SUNY, Albany, New York, United States
Show Abstract9:00 PM - V8.15
WITHDRAWN 02/21/08 Shapes of Semiconductor Nanostructures Epi-grown by Selective-area MOCVD.
Benzhong Wang 1 , Soo Jin Chua 1
1 MG, Institute of Materials Research and Engineering, Singapore Singapore
Show AbstractThursday, March 27WithdrawnPosterV8.15
9:00 PM - V8.16
Crystal Growth of Lead(II) Hydrate Benzoate.
Claudia Swanson 1 , Scott Oliver 1
1 Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California, United States
Show Abstract9:00 PM - V8.17
A Crystal Recognition Methodology for Systematic Quantitative Characterization of Nano-Scale Crystals.
Amjed Al-mousa 1 2 , Darrell Niemann 1 , Norman Gunther 1 , Mahmud Rahman 1
1 Electron Devices Laboratory, EE Dept., Santa Clara University, San Jose, California, United States, 2 , PDF Solutions, San Jose, California, United States
Show Abstract9:00 PM - V8.18
Electrochemical Shape Control and Shape-Dependent Properties of Cuprous Oxide Crystals.
Carrie Read 1 , Matthew Siegfried 1 , Kyoung-Shin Choi 1
1 Chemistry, Purdue University, West Lafayette, Indiana, United States
Show Abstract Morphological control capabilities are fundamentally important to tuning the properties and stabilities of a crystal. This is due to the direct relationship between shape and the interfacial atomic arrangement of a crystal. Therefore, controlling the shape can enhance the desired reactivity or stability of a material. This presentation will discuss electrochemical shape control of cuprous oxide crystals. Cuprous oxide can be cathodically deposited by reduction of copper (II) ions to copper (I) ions in an aqueous media. Production of copper (I) ions results in the precipitation of cuprous oxide due to the solubility limit of copper (I) ions. In order to systematically control shapes of cuprous oxide crystals, preferential adsorption of additives were exploited. When additives are introduced to the plating medium, they absorb on a certain crystallographic plane more strongly than on other planes. This adsorption hinders crystal growth perpendicular to the bound plane and alters the relative growth rate of crystals. Therefore, by identifying additives with varying adsorption preferences on cuprous oxide surfaces (e.g. {100}, {111}, and {110} planes), systematic and homogeneous shape control can be achieved. Various conditions and strategies to stabilize specific shapes of cuprous oxide will be discussed in detail in this presentation, which will be followed by discussions of shape-dependent electrochemical and photoelectrochemical properties of cuprous oxide crystals and films.
9:00 PM - V8.19
Degenerate Crystal Phases in Nonspherical Silica Colloids.
Stephanie Lee 1 , Sharon Gerbode 2 , Itai Cohen 2 , Chekesha Liddell 1
1 Materials Science & Engineering, Cornell University, Ithaca, New York, United States, 2 Physics, Cornell University, Ithaca, New York, United States
Show AbstractColloids are often used as models to elucidate fundamental principles in nucleation processes, phase transitions, and crystal growth behavior. Practically speaking, however, colloidal self-assembly is also an attractive means of forming the complex structures required in various photonic, optoelectronic, memory, and sensing applications. While progress has been made in these areas with spherical colloids, similar efforts that employ anisotropic shapes remain scarce primarily because nonspherical particles of sufficient monodispersity are more difficult to produce. In the present work, we describe a two-dimensional colloidal system that organizes into a phase (known as a “degenerate crystal”) predicted only by computer simulations to date. Our building block consists of micron-sized, nonspherical silica dumbbells synthesized via a sol-gel templating procedure. Such particles crudely approximate two fused spheres and may be considered as analogues to diatomic molecules on a colloidal length scale. Using confocal microscopy, the degenerate crystal (DC) is characterized for structure using both its center-of-mass (COM) as well as individual lobe positions. The results show good agreement with simulations in that (1) COMs were found to decorate aperiodic sites on a Kagomé lattice while (2) individual lobes occupied sites on a triangular lattice. Analysis of the DC phase by correlation functions, orientation mapping, and Voronoi constructions will be presented.
9:00 PM - V8.2
Synthesis of Large Scale Cu2O Nanocubes and Subsequent Oxidation to CuO Hollow Nanostructures for Lithium Ion Battery Anode Materials.
Ji Chan Park 1 , Hyunjoon Song 1 , Jeonghan Kim 2 , Hyuksang Kwon 2
1 Chemistry, Korea Advanced Institute of Science and Technology, Daejeon Korea (the Republic of), 2 Materials Science, Korea Advanced Institute of Science and Technology, Daejeon Korea (the Republic of)
Show AbstractIn recent years, semiconductor nanocrystals have attracted much attention because of their high activity, and unique electronic and optical properties. In particular, much research has been focused on cuprous oxide (Cu2O) and cupric oxide (CuO) nanostructures for gas sensors, heterogeneous catalysts, p-type semiconductors, and the negative electrodes for lithium ion batteries. In their application, the shape-controlled synthesis has important meaning in determining structural, physical, and chemical properties of them. So, various synthetic methods for Cu2O and CuO nanocrystals with varied morphology have been reported. Especially, Copper oxide materials with various morphology and size have exhibited their unique electrochemical performance as Li ion battery anode materials. Herein, we developed monodisperse ~50nm Cu2O nanocubes in large scale and facile method. Subsequently, the synthesized Cu2O nanocubes could be oxidized to about 100nm hollow cubes, hollow urchins, and urchins of the CuO phase by controlling water contents in aqueous ammonia solution. These CuO materials have different crystalline domain which can determine the efficiency and cycle property in battery materials. Electrochemical property in different morphology and crystalline domain size are also discussed with varied structure CuO nanomaterals as lithium ion battery anode materials.
9:00 PM - V8.20
Cyclic Growth Twinning of Sn in SnAgCu Alloys.
Eric Cotts 1 , Yan Xing 1 , Lawrence Lehman 1
1 , Binghamton University, Binghamton, New York, United States
Show Abstract9:00 PM - V8.21
Synthesis of Crystalline Lithium Niobate Nanostructures.
Bryan Wood 1 , Valentin Mocanu 1 , Byron Gates 1
1 Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada
Show Abstract9:00 PM - V8.23
The Effect of Transient Nucleation on the Microstructure in Nucleation and Growth Reactions.
David Wu 1 , Kevin Chu 1 2 , Siu Sin Quek 1 , Chin Yi Chee 1 , Jiawei Chiu 1
1 , Institute of High Performance Computing, Singapore Singapore, 2 , Vitamin D, Inc., Menlo Park, California, United States
Show Abstract9:00 PM - V8.24
Quantized Growth of CdTe Quantum Dots; Observation of Magic-Size and Controlling Aggregation Dynamics of CdTe Quantum Dots.
Pinar Dagtepe 1 , Viktor Chikan 1 , Jacek Jasinski 2 , Valerie Leppert 2
1 Chemistry, Kansas State University, Manhattan, Kansas, United States, 2 School of Engineering, University of California at Merced, Merced, California, United States
Show AbstractThis work presents experimental observation of the quantized growth of CdTe quantum dots (QD) in the presence of hexadecylamine (HDA), hexylphosphonic acid (HPA), and trioctylphosphine oxide (TOPO) above 200°C. The crystal growth of CdTe QDs is monitored by in situ UV-vis absorption spectroscopy. The high-temperature absorption spectra indicate the evolution of multiple peaks corresponding to various sizes of QDs. Analysis of different parameters shows that Cd/Te ratio is responsible for the quantized growth. Only in the Cd-rich conditions, just one excitonic peak appears and shifts to the longer wavelengths (larger sizes). And the reason for observation of quantized growth can be attributed to the different Cd/Te ratios. The high-resolution transmission electron microscopy (HRTEM) images and electron diffraction pattern show that most of the QDs have the zinc blende crystal structure, and they indicate nanotwinning and stacking faults in larger CdTe QDs. Domain sizes in the HRTEM images correlate well with the smallest observed magic-sized CdTe QDs, in agreement with the proposed aggregation growth mechanism under the experimental conditions. The smallest observed zinc blende CdTe QDs with the diameter of 1.9 ±0.3 nm are isolated by quenching the reaction mixture during the initial phase of the QD synthesis. The experimental observation suggests that the surprising stability of the magic-sized CdTe QDs is the result of the surface stabilization of the QDs of the HDA and/or HPA. As previously suggested, the aggregation is driven by dipole-dipole interaction between CdTe nanoparticles. The results show that the aggregation of quantum dots could be very important at the early stage of the growth. The magic-sized QDs can be dissolved in either methanol or toluene, which suggests heterogeneity of their surface chemistry. The QDs dissolved in the methanol phase exhibit relatively strong white light emission from 400 to 650 nm with an emission quantum yield of approximately 4%. The QDs dissolved in the toluene phase exhibit very weak emission.
9:00 PM - V8.26
WITHDRAWN 02/21/08 Synthesis of Template-free Zeolite Nanocrystals in Crosslinked Chitosan Hydrogels.
Dan Li 1 , Huanting Wang 1
1 Department of Chemical Engineering, Monash University, Melbourne, Victoria, Australia
Show AbstractThursday, March 27WithdrawnPosterV8.26
9:00 PM - V8.28
Implications of Hydrogen Bond Topologies onto Crystal Packing and Morphology.
Max Petersen 1 , Steffen Wilke 1
1 , Accelrys, Inc., San Diego, California, United States
Show Abstract9:00 PM - V8.29
Erbium Selenite Dihydrate Crystal Growth and Control; The Discovery of New Crystalline Structures.
Marc Bresler 1 , Claudia Swanson 1 , David Rogow 1 , Scott Oliver 1
1 Chemistry and Biochemistry, University California Santa Cruz, Santa Cruz, California, United States
Show AbstractThis presentation will describe a series of new erbium crystal structures, from a new metallic form, to the selenide and finally the selenite. The form is controlled through choice of synthesis conditions and reagents. Erbium oxide and selenium oxide gave rise to a new crystalline compound Er(SeO3)2×2H20 through hydrothermal synthesis. Two new crystalline polymorphs of erbium metal and erbium selenide have also been found. We have successfully reduced selenium oxide and erbium oxide to crystalline metal through hydrothermal synthesis and have found we are able to control not just crystal growth but oxidation and reduction of metals through adjusting the experimental hydrothermal conditions. Properties of these novel compounds were analyzed by powder and single crystal x-ray diffraction, TGA-MS, FTIR, DSC, and SEM.
9:00 PM - V8.3
Nanoreactor Frameworks for Heterogeneous Catalysts.
Jung Up Bang 1 , Joongoo Lee 1 , Ji Chan Park 1 , Hyunjoon Song 1
1 Chemistry, Korea Advanced Institute of Science and Technology, Daejeon Korea (the Republic of)
Show Abstract Colloidal metal nanoparticles have been interesting materials due to their catalytic applications. Despite their excellent catalytic activities, however, the catalytic properties have been limited to probe in that those are basically expected from the average value of significant amount of catalytic nanoparticles. Also, these systems cannot help avoiding the aggregation among the metal nanoparticles during the catalytic reaction. In this work, the ideal nanoreactor framework comprises a movable metal core and hollow silica shell, which can penetrate both the solvents and reactants. The reactants go inside of the silica shell and undergo catalytic reaction on the metal surface. Herein, we successfully synthesize Au@SiO2 and Ni@SiO2 nanoreactors by etching the gold and nickel nanoparticles selectively in core-shell structures, respectively. The average size of the metal cores could be readily tuned by using different amount of etchants. The synthesis of Au and Ni nanoparticle was confirmed by a polyol process in the presence of poly(vinyl pyrrolidone) as a surfactant and 1,5-pentandiol both as a reductant and as a solvent and the particles were coated with silica shells via the stober method. The Au@SiO2 framework can be employed for the catalytic reduction of p-nitrophenol as a model reaction and the Ni@SiO2 framework will be applicated to the Suzuki reaction.
9:00 PM - V8.30
Networks of Cross-Linked Nanocrystals.
Isabella Franchini 1 , Angela Fiore 1 , Albert Figuerola 1 , Stefan Kudera 2 , Roberto Cingolani 1 , Roman Krahne 1 , Liberato Manna 1
1 , NNL-National Nanotechnology Laboratory of CNR-INFM, Lecce Italy, 2 Metals Research, Max-Planck-Institute, Stuttgart Germany
Show Abstract9:00 PM - V8.31
Synthesis and Optical Properties of Tetrapod-like ZnSSe Alloy Nanostructures.
H. Xu 1 , Y. Liang 1 , Z. Liu 1 , X. Zhang 1 , S. Hark 1
1 Department of Physics, The Chinese University of Hong Kong, Hong Kong China
Show AbstractOne-dimensional (1D) semiconductor nanostructures have currently become a subject of intense research as building blocks for future nanodevices. In recent years, great efforts have been made to investigate 1D nanostructures of group II-VI semiconductors (e.g. ZnO, ZnS, ZnSe, CdS and CdSe), in large part due to their potential applications in optoelectronic and biological fields. Compared to binary compounds, their ternary alloys offer certain advantages, including continuously tunable band gaps and tailored physicochemical properties. For example, ternary semiconductor ZnSSe has a direct, wide band gap tunable from 2.7 to 3.7 eV, which make it suitable for developing short-wavelength light emitting diodes and laser diodes operating in the entire blue-violet region. However, due to the complexity of ternary and higher order phase diagrams, II-VI ternary alloys are technically difficult to grow into completely miscible, single crystalline nanostructures in the entire compositional range. Thus, the research on this aspect is very limited. Especially, it is to our knowledge that no report is available on 1D ZnSSe nanostructures. In this work, tetrapod-like ZnSSe alloy nanostructures with different compositions are synthesized by catalyst-free, normal pressure chemical vapor deposition. Different from the conventional tetrapod structure, our ZnSSe nanostructure consists of four long legs and four short ones. Two sets of tetrapod structures intertwine to form a novel nanoarchitecture. Every leg is a wurtzite-structured single crystal growing along the c axis. Possible nucleation and growth mechanisms of tetrapod-like structure are discussed. Micro-Raman scattering from single ZnSSe tetrapod displays a typical two-mode behavior, and the optical phonon frequencies strongly depend on the alloy compositions. Due to alloy disorder, the longitudinal optical phonon lines of ZnSSe alloy broaden asymmetrically compared to those of their binary compounds. These Raman results can be understood in terms of a random element isodisplacement model and a spatial correlation model. Cathodoluminescence measurements on an individual tetrapod find a strong near-band-edge emission peak, whose wavelength varies with its alloy compositions. Whereas commonly observed deep-level emissions associated with self-activated defects are suppressed. The successful fabrication of high-quality ZnSSe alloy nanosructures opens up the possibility of realizing short-wavelength nanolasers in the future.AcknowledgementsThe work described in this paper was partially supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. 2150521) and CUHK direct grants (Project codes: 2060305).
9:00 PM - V8.32
Synthesis and Characterization of Type II Core/Shell Quantum Dots ZnO/CdS.
Fen Xu 1 2 , Hiroshi Matsui 2 1
1 Chemistry Department, Graduate Center -CUNY, New York, New York, United States, 2 Chemistry Department, Hunter College - CUNY, New York, New York, United States
Show Abstract9:00 PM - V8.5
Structural and Optical Characterization of Silicon Nanocrystals in Atomic Scale by Ultra-high-vacuum Scanning Tunneling Microscopy.
Sung Won Hwang 1 , Sung Kim 1 , Seung Hui Hong 1 , Chang Oh Kim 1 , Suk-Ho Choi 1 , Yongsung Kim 2 , Ja Yong Koo 2
1 College of Electronics and Information, Kyung Hee University, Yongin, Kyungkido, Korea (the Republic of), 2 The Center for Atomic Control of Heteroepitaxy Group, Korea Research Institute of Standards and Science, Daejeon Korea (the Republic of)
Show Abstract9:00 PM - V8.6
Fabrication of Nanoparticles using Arc Plasma Gun.
Naoki Tsukahara 1 , Tomohiro Nagata 1 , Hirohiko Murakami 1
1 Tsukuba Institute for Super Materials, ULVAC, Inc., Tsukuba, Ibaraki Japan
Show AbstractNanoparticles have attracted great attention over the past couple of years due to their various applications specially their essential role as catalyst in fuel cell field. There are several methods for fabricating nanoparticles, and the liquid-phase method of precipitation method and sol-gel method is known. The nanoparticles can be simply synthesize using these methods, but high-temperature process and the restriction on the type of solutions used, are some of the main problems. Here we fabricate nanoparticles using Arc Plasma Gun (APG), designed and developed by ULVAC, Inc. Enabling low-temperature synthesis of nanoparticles, eliminating the need for inert gases such as Argon and operable in high vacuum, being able to vapor deposit any conducting material and freedom in choosing the substrate due to physical absorption are some of the main properties of using this method. By using APG, we consider that the problem in the liquid-phase method can improve. In this experiment we fabricated Pt nanoparticles by using APG while mixing carbon black (VULCAN XC-72). Carbon powder supported by Pt nanoparticles can be used as an electrode catalyst in fuel cell. We carried out the evaluation of the Pt nanoparticle by TEM observation. As a result, nanoparticles under TEM revealed an even formation of particles 2 -3nm in diameter. Further, we confirmed the fabrication of nanoparticles not only on carbon powder but also on an oxide powder and on CNTs which is considered a difficult in liquid phase method. From the above fact, the nanoparticles fabrication is simply possible, and the wide application can be expected.
9:00 PM - V8.7
Crystal Shape and Structure of Hydrothermal Synthesized iron-tin Mixed Oxide Nanocrystallites.
Valentin Teodorescu 1 , Marie-Genevieve Blanchin 2 , Monica Sorescu 3 , Lucian Diamandescu 1 , Doina Tarabasan-Mihaila 1
1 Stucture of Defects in Solids, National Institute for Materials Physics, Bucharest Romania, 2 Condense Mater Physics and Nanostructures Laboratory, Lyon 1 University, Villeurbanne France, 3 Department of Physics, Duquesne University, Pittsburgh, Pennsylvania, United States
Show Abstract9:00 PM - V8.8
Method to Create Cubic FePt Clusters During in situ Gas-Phase Aggregation.
Marlann Patterson 1 , Xiangxin Rui 2 , Jeff Shield 2 , David Sellmyer 2
1 Chemistry and Engineering Physics, University of Wisconsin - Platteville, Platteville, Wisconsin, United States, 2 MRSEC , University of Nebraska, Lincoln, Nebraska, United States
Show AbstractNanomagnetic cluster materials have wide applications as high-density storage media precursors [Xu, Yan, Sellmyer 2007]. Factors of ten increase in storage density are expected with the use of nanomagnetic clusters over present hard disc drive materials. Several methods to create nanomagnetic clusters exist, among them gas-phase aggregation in a sputter discharge. This method offers promise of a high degree of cluster property control. The nanomagnetic FePt clusters created in the gas phase normally develop a random fcc crystal structure. The ordered phase, however, is necessary to achieve magnetic coercivities commensurate with the memory industry’s future. Typically, a post-processing anneal is needed to achieve this ordered phase. However, JP Wang et al have shown that in situ anneal is possible [J-M Qiu, et al, 2006]. The method used by Wang to produce the cubic, ordered clusters is not well documented, however. Here, we present a method to create these cubic, ordered nanomagnetic FePt clusters in situ and propose a mechanism for the success of the method. There are two possible reasons why clusters may form cubes. (1) The plasma conditions offer long residence times and high ion-cluster collision probability. (2) Increased current to the target heats the target atoms before they form clusters. It is also possible that (3) both effects occur synergistically. In this study, cubic and spherical FePt clusters were created in an argon-helium dc sputter discharge under different flow and target power conditions. The plasma recipes for spherical and cubic clusters called for high He:Ar ratio, low target power and low He:Ar ratio, high target power, respectively. As measured by Langmuir probe and as expected, the recipes led to larger ion density for the cubic case (2x108cm-3 versus 6x106cm-3 for spherical). We conclude that the larger density of argon ions increased the cluster-ion collision probability, heating the clusters in situ to their anneal temperature, primarily according to mechanism (1) above.
9:00 PM - V8.9
Single-Crystal Nanoribbons, Nanotubes and Nanowires from Intramolecular Charge-Transfer Organic Molecules.
Zhang Xiujuan 1 , Lee Shuittong 1
1 , city university of HongKong, HongKong China
Show Abstract