Symposium Organizers
Paul Barnes Air Force Research Laboratory
Dominic Lee Oak Ridge National Laboratory
Chan Park Seoul National University
Naoyuki Amemiya Yokohama National University
Jodi Reeves SuperPower, Inc.
M1: HTS Conductor Challenges and Flux Pinning
Session Chairs
Tuesday PM, April 10, 2007
Room 3024 (Moscone West)
9:30 AM - **M1.1
Materials For Superconducting Magnets Beyond Niobium.
David Larbalestier 1
1 Applied Superconductivity Center, National High Magnetic Field Laboratory, Tallahassee, Florida, United States
Show AbstractIn spite of the great interest in applying HTS materials to electrotechnology, virtually all superconducting magnets made to date have been made from Nb-Ti or Nb3Sn. In spite of the helium cooling required, there are very good reasons for this – Nb wires are available in many designs and current capacities, twisted and filamentary, with overall current densities that are generally higher than any higher Tc materials, while also being strong and easily reinforced if greater strength is needed. They can operate in fields up to about 23T at 2K. But new demands, both for even higher fields beyond the Hc2 of any Nb compound, or for cryogen-free operation temperatures beyond the Tc are focusing new attention of Bi-2212, Bi-2223, YBCO and MgB2. Following the recommendations of COHMAG (Committee on High Magnetic Fields) and recent interests from the high energy physics community, new grand challenges of 30T NMR, 60T hybrid magnets and >50T solenoids for muon colliders are before the magnet community. The National High Magnetic Field Laboratory is proposing a major expansion of very high field magnet development using some or all of the above newer, higher Tc materials. I will review and discuss the materials challenges and options that such magnets pose.Work carried out in collaboration with Alex Gurevich, Eric Hellstrom, Denis Markiewicz and Justin Schwartz.
10:00 AM - M1.2
Materials Grand Challenges for Superconductivity
John Sarrao 1 , Wai-Kwong Kwok 2
1 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 2 , Argonne National Laboratory, Argonne, Illinois, United States
Show AbstractAs part of its effort to define transformational opportunities for fundamental research in energy security, the Department of Energy’s Office of Basic Energy Sciences held a workshop on Basic Research Needs for Superconductivity. The workshop identified a number of materials grand challenges and priority research directions for transforming the power grid to meet the needs of the 21st century. The prospect of moving from materials by serendipity to materials by design and of advancing the frontiers of epitaxial science to yield higher performing nano-structured architectures are two of the these challenges that could impact superconductivity research specifically and materials research more broadly. In this talk we highlight recent technical successes that motivate and illustrate these opportunities. We also discuss the science that might be necessary to accomplish these goals in the hopes of nucleating further community input and engagement.
10:30 AM - M1.4
Flux Pinning and Grain Boundary Enhancements of YBCO with Nanoparticle Additions
Timothy Haugan 1 , Paul Barnes 1 , Pierce Neal 1 , F Javier Baca 1 , Timothy Campbell 1 , Iman Maartense 1 , Timothy Peterson 1 , E. Stinzianni 2 , Manisha Rane 2 , Kathleen Dunn 2 , Pradeep Haldar 2 , Haiyan Wang 3
1 , The Air Force Research Laboratory, Wright-Patterson AFB, Ohio, United States, 2 College of Nanoscale Science and Engineering, SUNY - University of Albany, Albany, New York, United States, 3 Dept of Electrical and Computer Engineering, Texas A&M Univ., College Station, Texas, United States
Show AbstractRecent experiments to enhance both flux pinning and grain boundary (GB) properties of YBa2Cu3O7-z (YBCO or 123) coated conductors by 2nd phase nanoparticle additions will be summarized. Nanoparticles were added to YBCO films by pulsed laser deposition using alternating multilayers and mixed-composition single targets. Different material additions were considered with lattice mismatches varying from -12% to +10% compared to YBCO. Ca-doping was achieved with (Y1-xCax)2BaCuO5 phase additions, with x varying from 0.05 to 0.10 and overall Ca concentrations of the film varying from 0.25% to 0.5%. The flux pinning properties were studied to optimize critical current density (Jc) and pinning structures as a function of magnetic field (H), temperature (T) and angle of field applied (θ). Effects on GB’s were studied on SrTiO3 bicrystals with misorientation angles of (4-36)o. Results show that (50-1000)% improvements of GB transport currents at 77K can be achieved with both Y2CaCuO5 (211) nanoparticle addition and Ca-doping, with the improvement varying depending on film parameters, process conditions, and bicrystal angle. Nanoparticle additions optimized Jc(H,T,θ) properties at different H,T,θ regimes; e.g. some enhanced Jc at low H < 3T up to 300% whereas others provided strong pinning at H > 5T up to 500%. Microstructural and superconducting properties will be summarized for these studies, with particular emphasis on TEM analysis.
10:45 AM - M1.5
Influence of Ca-doping on Properties of Low Angle YBCO Grain Boundaries.
Sang-il Kim 1 , Alex Gurevich 1 , Yan Xin 2 , David Larbalestier 1
1 Applied Superconductivity Center, National High Magnetic Field Laboratory, Tallahassee, Florida, United States, 2 , National High Magnetic Field Laboratory, Tallahassee, Florida, United States
Show Abstract11:00 AM - M1.6
Determining Local Flux Pinning Properties with Micro and Nano Fabrication Techniques.
John Durrell 1 , Matt Feldmann 3 , Anna Palau 1 , Joffre Gutierrez 2 1 , Marcus Weigand 1 , Noel Rutter 1 , Judith MacManus-Driscoll 1 , Mark Blamire 1
1 Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom, 3 Materials Science and Engineering, University of Wisconsin, Madison, Wisconsin, United States, 2 , ICMAB, Barcelona Spain
Show AbstractWith the increasing sophistication of ReBCO materials for coated conductor applications and the complex interplay between grain and grain boundary properties it is becoming important to be able to study critical currents on ever smaller length scales. We have developed a family of techniques that allow the isolation of small sections of superconductor using both conventional lithography and focussed ion beam. In this way local variation of critical currents over micron length scales can be investigated. Furthermore by cutting appropriate structures it is possible to investigate the behaviour of currents flowing along the c-axis and indeed at any angle outside the a-b plane. Once isolated, our full range angular measurement capability allows the full characterisation of the vortex pinning is such small segments.We have demonstrated the power of combining these fabrication techniques by elucidating the vortex pinning in a range of structures. We show that the nature of YBCO grain boundaries on RABiTS substrates depends strongly on the growth route and that for in-plane fields the difference is largely due to the blocking of vortex channelling by meandering grain boundaries. We demonstrate that it is possible to access the c-axis properties of a thin film with a suitably engineered structure and determine the effect of pinning centres on c-axis current flow; this is of importance given the trend towards ever thicker conductors. Finally, for any combination of field, field orientation and temperature, by isolating individual grains and grain boundaries we can directly show how the properties of a conductor vary from place to place.
11:15 AM - M1: Challenge
BREAK
M2: Processing by MOD Deposition
Session Chairs
Mariappan Parathaman
Cees Thieme
Tuesday PM, April 10, 2007
Room 3024 (Moscone West)
11:30 AM - **M2.1
Crystal Growth Mechanism of TFA-MOD Derived YBCO.
Yuh Shiohara 1 , Teruo Izumi 1 , Masateru Yoshizumi 1
1 Superconducting Wires & Tapes, SRL-ISTEC, Koto-ku, Tokyo, Japan
Show Abstract12:00 PM - M2.2
Texture Development in 2-3 μm Thick YBCO Films Synthesized by BaF2 and MOD Processes on Metal RABiTS™ Substrates.
Vyacheslav Solovyov 1 , Harold Wiesmann 1 , Masaki Suenaga 1
1 Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York, United States
Show Abstract12:15 PM - M2.3
High Critical Current Density REBa2Cu3O7-x Thin Films Prepared by Fluorine-free Metalorganic Deposition Process.
Yoda Patta 1 , Daniel Wesolowski 1 , Michael Cima 1 , Takahiro Taneda 2 , Takeshi Kato 2
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 , Sumitomo Electric Industries, Ltd, Osaka Japan
Show Abstract12:30 PM - M2.4
High Ic Thick YBCO Films by Multiple Coating of Modified TFA-MOD Process
Yongli Xu 1 , Changhui Lei 2 , Rabi Bhattacharya 1
1 , UES Inc, Dayton, Ohio, United States, 2 , UIUC, Urbana, Illinois, United States
Show AbstractYBa2Cu3O7-d (YBCO) films through metallorganic deposition (MOD) approach are one of the most cost effective methods for long length coated conductor (CC) fabrications. Although, this process has shown success on films below 1 mm, Critical current (Ic) over 500 A/cm has not been demonstrated even on small samples. Increasing Ic through further improvement of Jc is not viable because the present Jcs are comparable to that of the intragrain Jc, which is believed to be the theoretical limit of the high temperature superconductor. YBCO thicker films through MOD approaches with pinning center enhancement are yet to be fully explored to attain higher Ics. Thus, in this paper, we present a multiple coating process to make thicker YBCO films through modified TFA-MOD approach. Thicker films of 1-2 mm with Ic over 280A/cm were successful grown by control of processing conditions. High growth rate up to 1 nm/s was realized on small samples. Non-superconducting second phase as pinning centers are studied by X-Ray diffraction and TEM observation. The mechanism of formation of well textured c-axis oriented YBCO thicker films with high-density pinning centers is proposed.
M3: REBCO Coated Conductor Processing
Session Chairs
David Larbalestier
Vladimir Matias
Tuesday PM, April 10, 2007
Room 3024 (Moscone West)
4:00 PM - **M3.1
Long-length, High-speed Manufacturing of High-performance Second-generation HTS Conductors.
Venkat Selvamanickam 1 , Yimin Chen 1 , Xuming Xiong 1 , Yi-Yuan Xie 1 , Jodi Reeves 1 , Andrei Rar 1 , Yunfei Qiao 1 , Ed Zhang 1 , Robert Schmidt 1 , Ken Lenseth 1
1 , SuperPower, Schenectady, New York, United States
Show Abstract4:30 PM - M3.2
Continuous Ribbons of Single Crystal Ni Films for HTSC Substrates.
Jae Shin 1 , Adam Standley 1 , Eric Chason 1
1 Division of Engineering, Brown University, Providence, Rhode Island, United States
Show AbstractHigh temperature superconducting wires or tapes are typically grown on textured metal substrates. The critical current that can be achieved depends strongly on the grain misorientation induced by the substrate. To fabricate substrates with a higher degree of orientational order, we have developed a process that can produce continuous films of Ni that consist of a single crystal. In the first stage of fabrication, single crystal layers of Cu and Ni are electrodeposited sequentially on a Ni (001) single crystal substrate. The Cu sacrificial layer is then selectively etched, and a free standing Ni (001) film is produced without damage to the Ni (001) film or substrate. By fabricating the starting substrate into a loop, it is possible to make the process continuous so that long ribbons of single crystal material can be produced. We present results on the initial fabrication of 5 mm x 5mm free standing single crystal Ni films using this process. The quality of the Cu (001) layer and Ni (001) film was measured by Scanning Electron Microscopy (SEM), Electron Backscatter Diffraction (EBSD), X-Ray diffraction (XRD), and Atomic Force Microscopy (AFM). The width of XRD rocking curves for the (002) diffraction peaks is less than 0.3 deg showing a high degree of ordering in the out-of-plane direction. EBSD orientational imaging indicates that the in-plane quality of the as-deposited Cu and Ni films are equivalent to the starting substrate for thicknesses up to 1µm, without any annealing of the film. These results indicate that epitaxially deposited single crystal films are potentially more highly ordered than texturing produced by mechanical means.
M4: YBCO Coated Conductors
Session Chairs
David Larbalestier
Vladimir Matias
Tuesday PM, April 10, 2007
Room 3024 (Moscone West)
4:45 PM - **M4.1
The Development of Second Generation HTS Wire at American Superconductor
Cornelis Thieme 1 , Marty Rupich 1 , Xiaoping Li 1 , Wei Zhang 1 , Yibing Huang 1 , Thomas Kodenkandath 1 , Nguyet Nguyen 1 , Dawood Aized 1 , John Voccio 1 , Darren Verebelyi 1
1 , American Superconducor, Westborough, Massachusetts, United States
Show AbstractAmerican Superconductor’s approach to development of a low-cost manufacturing process for Second Generation (2G) YBCO High Temperature Superconducting wire is based on a wide-strip (4 cm presently) process using a Metal Organic Deposition (MOD) process for the YBCO layer and the RABiTS (Rolling Assisted Biaxially Textured Substrate) process for the template. The wide-strip MOD-YBCO/RABiTS process is an attractive approach for commercial manufacturing due to the economies of wide-strip processing, high materials utilization and excellent performance. The process also provides the flexibility to engineer practical 2G conductors with architectures and properties tailored for specific applications and operating conditions. The MOD YBCO process allows the controlled introduction of pinning centers into the superconducting film enabling optimization of the magnetic field performance for applications with different temperature and magnetic field requirements. Its optimization and incorporation of specific pinning centers into the YBCO layers for different field angles have enabled significant improvement in the 2G wire performance. We will review the status of the 2G manufacturing scale up at AMSC and describe the properties and architecture of the 2G wire being developed and tested for various applications including coils and cables.
5:15 PM - M4.2
Preparation of Substrates for Improved Coated Conductor Performance
Vladimir Matias 1 , Jens Hänisch 1 , Jonathan Storer 1 , John Rowley 1 , Noriyuki Kumasaka 2
1 MPA-STC, Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 2 , MIPOX International Corporation, Hayward, California, United States
Show AbstractWe examine the influence of various substrate preparation procedures for IBAD-MgO based coated conductors. IBAD-MgO nano-texturing is very sensitive to the nucleation surface. Surface roughness has an important influence on the texture of the MgO layer. However, the shape of the surface also affects the texturing process. We use Hastelloy C-276 metal alloy as the substrate. The untreated substrate is leveled by either electropolishing, mechanical polishing or solution deposition. All three methods are applied to continuously moving tapes in long lengths. The RMS surface roughness decreases from 20 nm for the untreated substrate to 0.5 nm, 0.3 nm and 2 nm respectively. The in-plane texture of the MgO layer improves as the roughness is decreased. Other variations in the polishing procedures will be discussed such as polishing of the solution deposited layers. We study the surfaces using atomic force microscopy. In situ monitoring of the films is done with reflection high-energy electron diffraction (RHEED) and ion scattering spectroscopy. X-ray diffraction is done on the textured films to analyze the quality of the biaxial alignment. In the best cases the MgO layer has an in-plane mosaic FWHM of 2° and out-of-plane FWHM of 1°. The quality of the YBCO films deposited on top of the IBAD layers will be discussed in terms of their Jc and magnetic field performance. Analysis of the optimal and minimum required substrate conditions will be presented.This work is supported by the Department of Energy Office of Electricity Delivery & Energy Reliability.
5:30 PM - M4.3
Multi-functional Buffer Layers for YBCO Coated Conductors
Mariappan Paranthaman 1 , S. Sathyamurthy 1 , M. Bhuiyan 1 , T. Aytug 1 , A. Goyal 1 , T. Kodenkandath 2 , X. Li 2 , W. Zhang 2 , M. Rupich 2 , X. Xiong 3 , Y. Chen 3 , V. Selvamanickam 3
1 , Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States, 2 , American Superconductor Corporation, Westborough, Massachusetts, United States, 3 , SuperPower, Inc., Schenectady, New York, United States
Show AbstractBoth RABiTS and IBAD-MgO templates have been used to fabricate high performance YBCO coated conductors. Buffer layers play a key role in YBCO 2G wire technology. The purpose of the buffer layers is to provide a continuous, smooth and chemically inert surface for the growth of the YBCO film, while transferring the biaxial texture from the substrate to the HTS layer. Important buffer layer characteristics are to prevent metal diffusion from the substrate into the superconductor, as well as, to act as oxygen diffusion barriers. U.S. HTS wire manufacturers are now in a position to produce high quality coated conductors in “pilot-scale” mode. Whether or not the DOE cost target can be achieved, however, depends greatly on increasing the throughput, decreasing the buffer thickness, lower-cost deposition process and simplifying the conductor architecture. This will require novel buffer materials with multi-functional properties. We have developed a low-cost, non-vacuum, chemical solution deposition process to grow highly aligned La2Zr2O7 and CeO2 buffers towards all MOD buffer/YBCO. We have also developed a high rate sputtered LaMnO3 buffer for IBAD-MgO template compatible for high rate MOCVD process. We will report in detail about the current status of the results achieved using these buffers._____________Reserarch supported by the U.S. DOE, Division of Materials Sciences, Office of Science, and Office of Electricity Delivery and Energy Reliability. The research was performed at the Oak Ridge National Laboratory, managed by UT-Battelle, LLC for the USDOE under contract DE-AC05-00OR22725
5:45 PM - M4.4
Advanced Buffer Layer Architectures for YBCO Coated Conductors.
Sebastian Engel 1 , Bernhard Holzapfel 1 2 , Ludwig Schultz 1 2 , Oliver de Haas 1
1 Substrates, evico GmbH, Dresden, Saxony, Germany, 2 Superconducting Materials, IFW-Dresden, Dresden, Saxony, Germany
Show AbstractM5: Poster Session: Progress in High Temperature Superconductors I
Session Chairs
Matt Feldmann
Chakrapani Varanasi
Wednesday AM, April 11, 2007
Salon Level (Marriott)
9:00 PM - M5.1
Nano-scale Pinning Centers in Melt-Textured-Growth Sm-Ba-Cu-O Superconductor
Shih-Yun Chen 1 2 , Alexandre Gloter 2 , Christian Colliex 2 , In-Gann Chen 3 , Maw-Kuen Wu 1
1 , Institute of Physics, Academia Sinica, Taipei Taiwan, 2 Laboratoire de Physique des Solides, CNRS-UMR 8502, Université Paris Sud, Paris France, 3 Department of Materials Science and Engineering, National Cheng-Kung University, Tainan Taiwan
Show AbstractSm-Ba-Cu-O (SmBCO) materials doped with nano-scale RE2BaCuO5 (nmRE211, RE=Y, Sm and Nd) exhibit superior superconductivity in high magnetic fields. According to the results of transport behavior analysis and the knowledge of growth mechanism, the existence of nano-scale compositional fluctuations was suggested. To further elucidate the characteristics of the compositional fluctuation regions, in this study, microstructure of nano-scale Y2BaCuO5 (nmY211) doped SmBCO materials were investigated using transmission electron microscopy (TEM) and electron energy loss spectra (EELS). In addition to the regions with higher content of Y, of which a higher density of defects were found, nano-scale periodic structures with width range from several to several tens nm were observed throughout the matrix. Notably, the periodic structure was also observed in SmBCO samples without nmY211 addition. The chemical distribution, valence structure, thickness, and crystal structure in these periodic structures of SmBCO samples with and without nmY211 additions were compared with those found in the NEG ((Nd, Eu, Gd)-Ba-Cu-O) materials. Finally, a hypothesis explaining the effect of these periodic structures on flux motion, and then act as pinning centers in high field regions was also proposed in this study.
9:00 PM - M5.10
Pinning Strength, Mechanisms, and Dimensionality in YBCO PLD with Various Types of Artificial Pinning Structure-Based Enhancements
Mike Sumption 1 , Tim Haugan 2 , Paul Barnes 2 , Chakrapani Varanasi 2 , Tim Campbell 2
1 Material Science , Ohio State, Columbus, Ohio, United States, 2 Propulsion Directorate, Air Force Research Laboratory, Dayton, Ohio, United States
Show AbstractMagnetic measurements of PLD-YBCO samples with nanoparticle additions and chemical substitutions will be described, and the results are correlated with studies of flux pinning mechanisms. Nanoparticles were added to YBCO by PLD either in the form of multilayers or as random 3-D distributions. Various 211 layer spacings were investigated for the 211 layered samples. Additionally, minute doping of various additions, as well as BZrO3 and Ba-Sn-O additions were investigated. The samples were first characterized by magnetic Jc measurements from 4 K to 77 K. The results very generally show an increase in Jc for various kinds of inclusions and dopants. Additionally, ramp rate measurements of the magnetization creep were performed on various doped (pinned) and control samples, showing increases in pinning strength, in this case interpreted within the context of the collective pinning model, and specifically in terms of the temperature independent parameter Uc0; values in the 250-600 K range were observed. The glassy exponent was determined to be roughly 0.75-0.78, arguing for 3-D pinning mechanisms. After this, direct creep measurements (ramp-to-field and hold) were analyzed, and the results seen to agree with the ramp rate measurements. Field and temperature scaling were explored, and a set of scaling functions for the U vs J curves determined and compared to theoretical expectation (from the collective pinning model). Alpha factors were extracted, and seen to be significantly reduced for “pinning” samples, reaching as low as 0.2, a result which is of strong technical interest. Finally, a discussion is made which attempts to bring together a number of experimental results for the pinning and creep in the YBCO samples, and an argument for a 3-D pinning based on lattice strains and/or distortions is advanced.
9:00 PM - M5.12
Modification of Electron Beam Co-evaporated YBCO Precursor for Faster Ex-situ Conversion.
Yifei Zhang 1 , Ron Feenstra 1 , David Christen 1
1 Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
Show AbstractBaF2-based e-beam co-evaporated precursor conversion is one of the ex-situ processes being developed for the cost-effective fabrication of YBa2Cu3O7-δ (YBCO) coated conductors. At a given processing condition the precursor conversion behavior in terms of its reaction mode and epitaxy capability strongly depends on the precursor crystallinity and chemistry. It has been found that an intermediate precursor treatment facilitates faster conversion by enabling c-axis YBCO growth under more reactive processing conditions. The pre-treatment modified the precursors by pre-crystallizing the structure and altering the cation chemical states. The precursor modification appears more important for thicker precursors than for thinner precursors. Films at different processing stages were investigated with various techniques for understanding the correlation between the precursor characteristics and the conversion behaviors. Preliminary results indicate that to effectively enable a faster conversion for thicker precursors a through-thickness structural or chemical gradient in the precursor may be useful.Research sponsored by the U.S. Department of Energy, Office of Electricity Delivery and Energy Reliability, Superconductivity Program for Electric Power Systems, under contract No. DE-AC05-00OR22725 with UT-Battelle, LLC.
9:00 PM - M5.2
Enhancement of High Field Jc in Large Grain Y-Ba-Cu-O Superconductor by Infiltration Growth Method
Yung-Sheng Hsiao 1 , Chun-Chih Wang 1 , In-Gann Chen 1
1 Department of Material Science and Engineering, National Cheng Kung university, Tainan Taiwan
Show Abstract9:00 PM - M5.3
YBa2Cu3Ox Thick Films Produced by Electrophoretic Deposition on Ni and Ag Substrates.
Laurent Dusoulier 1 2 , Samuel Denis 3 2 , Michel Dirickx 2 , Philippe Vanderbemden 3 , Marcel Ausloos 4 , Rudi Cloots 1 , Benedicte Vertruyen 1
1 Chemistry, University of Liege, Liege Belgium, 2 , Royal Military Academy, Brussels Belgium, 3 Engineering, University of Liege, Liege Belgium, 4 Physics, University of Liege, Liege Belgium
Show Abstract9:00 PM - M5.4
Development of High Strength, Low Magnetism and Strongly Cube-textured Ni-7%W/Ni-10%W Composite for Coated Superconductor.
Danmin Liu 1 , Fei Hao 1 , Jiuxing Zhang 1 , Yancao Hu 1 , Shenlin Zhou 1 , Meiling Zhou 1
1 , Beijing University of Technology, Beijing China
Show Abstract9:00 PM - M5.5
YBa2Cu3O7-x Coatings on Flexible YSZ Ceramic (Ceraflex) Substrates for Low ac Loss Applications with IBAD -MgO and PLD- LaMnO3 Cap Layers.
Chakrapani Varanasi 1 , J. Burke 1 , P. Barnes 2 , I. Maartense 1 , R. Lu 3 , J. Wu 3
1 Metals & Ceramics, Unversity od Dayton Research Institute, Dayont, Ohio, United States, 2 AFRL/PRPG , Airforce Research Laboratory, WPAFB, Ohio, United States, 3 Department of Physics and Astronoy, University of Kansas, Lawrence, Kansas, United States
Show Abstract9:00 PM - M5.6
MOD-processed YBCO Coated Conductor on the IBAD MgO Template.
Geo-Myung Shin 1 , Rock-Kil Ko 2 , Kyu-Jung Song 2 , Jae-Moo Yoo 3 , Chan Park 1 , Seung-Hyun Moon 4 , Sang-Im Yoo 1
1 Material Science & Engineering, Seoul National University, Seoul Korea (the Republic of), 2 Advanced and Applied Materials Laboratory, Korea Electrotechnology Research Institute, Changwon, Kyungnam, Korea (the Republic of), 3 High Temperature Superconducting Wire Laboratory, Korea Institute of Machinery & Materials, Changwon, Kyungnam, Korea (the Republic of), 4 , SuNAM Co., Ltd, Anyang, Gyeonggi, Korea (the Republic of)
Show Abstract9:00 PM - M5.9
Progress in the Development of Tunable, High-Current MOD YBCO Films for Coated Conductors
Terry Holesinger 1 , Boris Maiorov 1 , James Coulter 1 , Leonardo Civale 1 , Victor Maroni 2 , Dean Miller 2 , D. Feldmann 3 , David Larbalestier 3 , Xiaoping Li 4 , Yibing Huang 4 , Wei Zhang 4 , Martin Rupich 4
1 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 2 , Argonne National Laboratory, Argonne, Illinois, United States, 3 , Florida State University, Tallahassee, Florida, United States, 4 , American Superconductor, Westborough, Massachusetts, United States
Show AbstractHigh critical current densities (Jc) in YBa2Cu3Oy (YBCO) coated conductors depend directly upon the defect types and densities within the films. The challenge for developing a viable wire technology involves, on one hand, the ability to introduce controlled defect structures that are sufficient for tailoring the properties to the temperature and magnetic field conditions required for operation and, on the other hand, to maintain those properties across the tape width and over hundreds-of-meter lengths. That is, the coated conductors must contain engineered inhomogeneities on the nano-scale, while being homogeneous on the macro-scale. The characteristic microstructures and defect structures are discussed for YBCO films made by the metal organic deposition (MOD) of trifluoroacetate-based precursors and subsequent furnace conversions. A main focus of this work is connecting key process-dependent, nanostructural features with their corresponding macroscopic expression of critical current densities in these coated conductors and the ability to tune these properties via nano-engineering of the defect structure to meet a variety of application conditions.
Symposium Organizers
Paul Barnes Air Force Research Laboratory
Dominic Lee Oak Ridge National Laboratory
Chan Park Seoul National University
Naoyuki Amemiya Yokohama National University
Jodi Reeves SuperPower, Inc.
M6: MgB2 Deposition and Properties
Session Chairs
Herbert Freyhardt
Amit Goyal
Wednesday AM, April 11, 2007
Room 3024 (Moscone West)
9:30 AM - **M6.1
Processing and Superconducting Properties of MgB2 Tape Conductors.
Hiroaki Kumakura 1 , Hiroshi Kitaguchi 1 , Takayuki Nakane 1 , Akiyoshi Matsumoto 1 , Hideyuki Yamada 2 , Nobuhito Uchiyama 2
1 , National Institute for Materials Science, Tsukuba Japan, 2 , Central Japan Railway Company, Komaki Japan
Show Abstract10:00 AM - M6.2
Comparison of Different Carbon Dopants and Their Effect on the Superconducting Properties of Mechanically Alloyed MgB2.
Marko Herrmann 1 , Wolfgang Haessler 1 , Christian Rodig 1 , Margitta Schubert 1 , Bernhard Holzapfel 1 , Ludwig Schultz 1 2
1 Institute of Metallic Materials, IFW Dresden, Dresden Germany, 2 Department of Physics, Dresden University of Technology, Dresden Germany
Show AbstractDoping with Carbon both in its elemental state and as carbon containing compounds, e.g. the strongly investigated SiC, seems to be the method of choice in enhancing the superconducting properties of MgB2 wires and tapes.Doped and undoped precursor powders were prepared by mechanical alloying. This ambient temperature preparation was successfully applied to obtain nanocrystalline, partially reacted precursor powders for sintering of bulk samples and wire fabrication by the Powder-In-Tube method. The high reactivity of the milled powders promotes the formation of MgB2 at reduced temperatures around 650°C to 700°C. Compared to other in situ preparation techniques bulk samples of undoped mechanically alloyed MgB2 show a high jc of 1 x 106 A/cm2 in self-field at 7.5 K and critical fields Hc2 of 20 T. This can be explained due to the high density of grain boundaries, which act as pinning centers and enhance the critical current density remarkably. We will present a comparison of promising Carbon dopants like nano-Diamond, Carbon nanotubes and nanocrystalline Silicon carbide. Their influence on the critical temperature of the transition, lattice parameter, critical field and critical current density of bulk and tape samples will be discussed. Optimal doping levels of Carbon containing compounds in a range up to 5 wt.% lead to further improvement of critical fields up to 30 T at 0 K. At the same time the field dependence of jc is decreased and the samples show an improved critical current density for higher magnetic fields. An observed change of the lattice parameters points clearly on a Carbon substitution of Boron sites in the lattice of MgB2.
10:15 AM - M6.3
XPS Studies of MgB2 Thin Films and Surface Oxides.
John Read 1 , Robert Buhrman 1 , Brian Moeckly 2 , Yi Cui 3 , Xiaoxing Xi 3
1 , Cornell University, Ithaca, New York, United States, 2 , Superconductor Technologies, Inc. , Santa Barbara, California, United States, 3 , Pennsylvania State University, University Park, Pennsylvania, United States
Show Abstract10:30 AM - M6.4
MgB2 Phase Formation and Transport Properties in Multifilamentary Strands
Mike Sumption 1 , E. Collings 1 , M. Bhatia 1 , Mike Susner 1 , Scot Bhonenstiel 1 , Mike Tomsic 2
1 Material Science , Ohio State, Columbus, Ohio, United States, 2 , Hyper Tech Research, Columbus, Ohio, United States
Show AbstractTypical performance values in MgB2 strands are presented, including present filament size, stability, and high-field transport Jc levels. The limitations in Jc of MgB2 are discussed, with emphasis on pinning, Bc2, and connectivity. Bc2 and irreversibility measurements made at different current levels are detailed; measurements made in the force-free direction allow clarification with respect to irreversibility and critical field measurements. The “tail” of the Jc response is explored. The influence of Mg/B stoichiometry on high field (10 T) Jc is shown, with best results (104 A/cm2) seen for 15% excess Mg). Fp scaling/non-scaling is discussed for strands with various dopants, including SiC. The formation of MgB2 from precursors is discussed in terms of DSC reactions, clarifying the effects of the native oxide layers present on the starting powders and showing that the reaction to MgB2 for high quality B powders is a solid-state diffusion reaction even when the final reaction temperature is in the 657-700°C range above the melting point of Mg. Finally, the influence of Mg/B ratio and SiC dopants on the microstructure is shown and discussed, with an emphasis on grain connectivity.
10:45 AM - M6.5
Kinetics Measurements and Numerical Simulation of Synthesis of MgB2 Fibers.
John DeFouw 1 , John Quintana 2 1 , David Dunand 1
1 Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States, 2 Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, United States
Show AbstractBoron fibers with 140 μm diameter were reacted to MgB2 in liquid magnesium at temperatures between 700 °C and 1000 °C. The radial growth of layers of MgB2 as well as the intermediate phases of MgB4 and MgB7 was measured on polished cross sections of partially reacted fibers and fit to a cylinder reaction model to determine diffusion coefficients. Diffusion coefficients for MgB2 ranged from 2 x 10-17 m2/s at 700 °C to 6 x 10-13 m2/s at 1000 °C with an activation energy of 360 kJ/mol. Activation energies for the radial growth of the MgB7 and MgB4 phases were 320 kJ/mol and 480 kJ/mol respectively. While these diffusion coefficients predict a very long time for completion of the reaction, it was also observed that the MgB4 layer cracked during the reaction, allowing magnesium to infiltrate into the cracks and short circuit the diffusion-only growth process for much faster reaction times. This process was simulated numerically and compared to in-situ experiments where the reaction kinetics of fibers were measured using synchrotron x-ray diffraction. In-situ measurements of reaction time were closely approximated by the simulation.
11:00 AM - M6: MgB2
BREAK
M7: Magnetic Flux Pinning in REBCO Superconductors I
Session Chairs
Boris Maiorov
Yutaka Yamada
Wednesday PM, April 11, 2007
Room 3024 (Moscone West)
11:30 AM - **M7.1
Enhanced Flux-pinning in Coated Conductors via 3D Self-Assembly of Insulating Nanodots in REBCO Films on RABiTS and IBAD Substrates.
Amit Goyal 1 , Sung-Hun Wee 1 , Jing Li 1 , Sukill Kang 1 , Patrick Martin 1 , Mariappan Paranthaman 1 , Lee Heatherly 1
1 , OAK RIDGE NATIONAL LABORATORY, OAK RIDGE, Tennessee, United States
Show Abstract12:00 PM - M7.2
Enhancement and Analysis of Flux Pinning in YBa2Cu3O7 Films by Nanoparticle-modified Substrate Surfaces.
Tolga Aytug 1 2 , M. Paranthaman 1 , K. Kim 1 , S.H. Wee 1 , K. Leonard 1 , A. Gapud 1 , P. Martin 1 , A. Goyal 1 , A. Ijaduola 2 , J. Thompson 2 1 , D. Christen 1 , R. Meng 3 , I. Rusakova 3
1 , Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States, 2 , University of Tennessee, Knoxville, Tennessee, United States, 3 , University of Houston, Houston, Texas, United States
Show Abstract12:15 PM - M7.3
Enhanced Flux Pinning in YBa2Cu3O7-δ Thin Films by Incorporating Semi-continuous Nanolayers.
Haiyan Wang 1 2 , Jongsik Yoon 1 , Roy Araujo 1 , Steve Foltyn 2 , Quanxi Jia 2 , Honghui Zhou 2 , Boris Maiorov 2 , Leonardo Civale 2 , Judith MacManus-Driscoll 3 , Xinghang Zhang 4
1 Electrical and Computer Science, Texas A & M University, College Station, Texas, United States, 2 Superconductivity Technology Center, Los Alamos National Lab, Los Alamos, New Mexico, United States, 3 Department of Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom, 4 Department of Mechanical Engeering, Texas A & M University, College Station, Texas, United States
Show Abstract12:30 PM - M7.4
Combination of Nanopores and Nanorods increases overall Jc(B,θ) in YBa2Cu3O7-δ
Rose Lyn Emergo 1 , Judy Wu 1 , Javier Baca 1 , Timothy Haugan 2 , Paul Barnes 2
1 Physics and Astronomy, University of Kansas, Lawrence, Kansas, United States, 2 , Air Force Research Laboratory (AFRL), Wright-Patterson AFB, Ohio, United States
Show AbstractBaZrO3 (BZO) nanorods were generated in highly porous YBa2Cu3O7-δ (YBCO) films on vicinal SrTiO3 substrates using pulsed laser deposition (PLD). The microstructure study of the films revealed that the pore size was dramatically reduced by the insertion of the BZO nanorods. In addition, the BZO nanorod alignment along the c-axis was broadened in these samples. This results in overall enhanced critical current density Jc in the applied magnetic field B range of 0.1-5 Tesla when B is perpendicular to the film, which is attributed to the aligned BZO nanorods. In addition, significant Jc enhancement was also confirmed in other orientation of the B field, suggesting that the combination of the nanorods and nanopores may reduce the damage on the ab-planes caused by nanorod insertion and thus led to increased overall Jc(B,θ). It should be mentioned that the insertion of the BZO nanorods slightly reduced the lower field Jc of the porous YBCO. For example, the Jc decreased from 8 MA/cm2 to 6.5 MA/cm2 at 0T and 77K. This could be due to the slight reduction of superconducting volume portion when BZO nanorods were generated inside the porous YBCO film which is also consistent with reported results of YBCO films doped with different kinds of nanomaterials except for nanopores. However, this Jc value is still higher than the Jc of standard PLD YBCO film.
12:45 PM - M7.5
Enhanced High-field Performances in PLD Films Fabricated by YSZ-added YBa2Cu3O7-x Targets.
Paolo Mele 1 2 , Kaname Matsumoto 1 2 , Tomoya Horide 1 2 , Ataru Ichinose 3 2 , Masashi Mukaida 4 2 , Yutaka Yoshida 5 2 , Shigeru Horii 6 2
1 Materials Science and Engineering, Kyoto University, Kyoto Japan, 2 , CREST-JST, Saitama Japan, 3 , CRIEPI, Yokosuka Japan, 4 Material Science and Engineering, Kyushu University, Fukuoka Japan, 5 Electrical Enginnering and Computer Science, Nagoya University, Nagoya Japan, 6 Applied Chemistry, Tokyo University, Tokyo Japan
Show AbstractM8: Magnetic Flux Pinning in REBCO Superconductors II
Session Chairs
Timothy Haugan
Takanobu Kiss
Wednesday PM, April 11, 2007
Room 3024 (Moscone West)
2:30 PM - **M8.1
Unique Pinning and Enhanced Irreversibility Field for YBa2Cu3O7-x Films with BaSnO3 Nanoparticles
Chakrapani Varanasi 1 , P. Banes 2 , J. Burke 1 , I. Maaretense 1 , K. Dunn 3
1 Metals & Ceramics, University of Dayton Research Institute, Dayton, Ohio, United States, 2 AFRL/PRPG , Airforce Research Laboratory, WPAFB, Ohio, United States, 3 , College of Nanoscale Science & Engineering, University at Albany - State University of New York, Albany, New York, United States
Show AbstractNanoparticles of BaSnO3 of the average size of ~10 nm and in a number density of 3.5 x10 exp 11 particles/cm2 were introduced into YBa2Cu3O7-x (YBCO) films using a dual sector pulsed laser ablation target consisting of YBCO and BaSnO3 sectors. Films of YBCO+BaSnO3 on (100) Lanthanum aluminate single crystal substrates showed marked improvements (especially at high fields) in critical current density (Jc) determined by both transport and magnetization measurements compared to regular YBCO films. An order of magnitude improvement in Jc at 5-6 T at 77 K was observed. Angular dependence data showed Jc (H//c) was almost 1.3 times the value of Jc (H//ab) indicating a strong presence of c-axis correlated pining centers. YBCO+BaSnO3 films were also deposited on buffered metallic substrates and similar improvements were observed. The data on these samples will be presented. In addition, the position of the maximum of the bulk pinning force curve, Fp,max, occurred at more than half of Hirr in quality YBCO+BaSnO3 thin films as opposed to the typical ~0.3 Hirr. The irreversibility field (Hirr) in YBCO+BaSnO3 was also found to be increased to ~ 8.5 T at 77 K. Further, we present a unique, distinguishable dual-pinning structure that was observed in these films for which the pinning mechanisms were found to be neither fully additive nor completely independent of each other.
3:00 PM - M8.2
Enhanced Flux Pinning in YBCO Layers by the Formation of Nanosized BaHfO3 Precipitates Using the Chemical Deposition Method.
Bernhard Holzapfel 1 3 , Sebastian Engel 1 2 , Thomas Thersleff 1 2 , Ruben Huehne 1 , Ludwig Schultz 1 2 3
1 Superconducting Materials, IFW-Dresden, Dresden, Saxony, Germany, 3 Department of Physics, Institute for Physics of Solids, Dresden University of Technology, Dresden, Saxony, Germany, 2 Department of Mechanical Engineering, Institute of Material Science, Dresden University of Technology, Dresden, Saxony, Germany
Show Abstract3:15 PM - M8.3
Weak Thickness Dependence of Jc and Responsible Features of Microstructure in a Strong Pinning YBCO Film.
Fumitake Kametani 1 , Sang Il Kim 1 , David Larbalestier 1 , Timothy Haugan 2 , Paul Barnes 2
1 Applied Superconductivity Center, NHMFL, FSU, Tallahassee, Florida, United States, 2 , Air Force Research Laboratory, Dayton, Ohio, United States
Show Abstract3:30 PM - M8.4
Superconducting and Microstructural Properties of (Y1+y-xEux)Ba2-yCu3O7-z Thin Films: x = 0.0 to 1.0 and y = 0 to 0.1
Timothy Haugan 1 , Neal Pierce 1 , F Javier Baca 1 , Timothy Campbell 1 , David Blubaugh 1 , B Craig Harrison 1 , Iman Maartense 1 , Paul Barnes 1
1 , The Air Force Research Laboratory, Wright-Patterson AFB, Ohio, United States
Show AbstractThe superconducting and microstructural properties of (Y1+y-xEux)Ba2-yCu3O7-z thin films was studied for complete Eu substitution (x = 0 to 1) and small RE substitution on the Ba site (y = 0 to 0.1). Previously our group studied the (Y1-xEux)123 system for x = 0 to 1 and no substitution on the Ba site (y = 0). In these previous studies, a CeO2-buffer-YSZ substrate was observed to optimize the film properties. For optimized films with Eu = 0.3 to 0.5, high values of Jc self-field ~5 MA/cm2 were achieved. Additionally, there was a ~2x increase of Jc(H//ab-plane>0T) and Jc(H//c-axis<0.5T) compared to Y123-only films. The present work extends these studies by focusing mostly on substitution on the Ba site for Eu = 0.3 to 0.5 compositions. Additional work tests new M-CeO2-buffer layer structures to further increase Jc(H) properties, and particularly for Ba-substituted and Eu > 0.5 where the (Y,Eu)123 films can have problems with a-axis growth. Initial results indicate that some Ba-substituted compounds increase Jc(H//c-axis) at 65K-77K, compared to Y123. Also the Tc measurements show interesting trends, actually increasing with Ba substitution rather than the opposite effect expected from trends measured in bulk powders. This paper summarizes systematic studies of these (Y,Eu)123-type films.
3:45 PM - M8.5
Microstructural and Superconducting Properties of (Eu0.33Y0.67)Ba2Cu3O7-δ
Honghui Zhou 1 , Boris Maiorov 1 , Scott Baily 1 , Haiyan Wang 2 , Judith MacManus-Driscoll 3 , Terry Holesinger 1 , Leonardo Civale 1 , Quanxi Jia 1 , Stephen Foltyn 1
1 Superconductivity Technology Center, Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 2 Department of Electrical and Computer Engineering, Texas A & M University, College Station, Texas, United States, 3 Department of Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom
Show AbstractCompared with YBa2Cu3O7-δ, rare-earth (RE) based superconducting films, such as REBa2Cu3O7 (RE123, where RE=Nd, Sm, Eu, …) exhibit better surface morphology and often better performance in magnetic field. Nevertheless, the successful growth of high-quality RE123 films requires extremely demanding processing conditions. For example, a substrate temperature of 850 °C is needed for high performance EuBa2Cu3O7-δ films if grown without a seed layer. In this presentation, we report rare earth doped superconducting films (Eu0.33Y0.67)Ba2Cu3O7-δ of different thickness grown on single crystal SrTiO3 substrates by the pulsed laser deposition. Film surface morphology, crystalline perfection and microstructure were investigated by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and cross-sectional Transmission Electron Microscopy (TEM), respectively. Critical current densities in self-field and applied magnetic fields were also measured. The results show that (Eu0.33Y0.67)Ba2Cu3O7-δ films have a smoother microstructure with no indication of a axis (perpendicular to the surface) grains or 45 ° in-plane rotated grains, unlike YBa2Cu3O7-δ deposited under the same conditions. These films also exhibit enhanced in-field critical current density. The thickness dependence of the self-field critical current density will be also discussed.
M9: Magnetic Flux Pinning in REBCO Superconductors III
Session Chairs
Hiroaki Kumakura
Michael Sumption
Wednesday PM, April 11, 2007
Room 3024 (Moscone West)
4:15 PM - M9.1
Grand Challenges for Vortex Matter Research
Wai-Kwong Kwok 1 , John Sarrao 2
1 Materials Science Division, Argonne National Laboratory, Argonne, Illinois, United States, 2 Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show AbstractThe DOE Basic Energy Sciences Workshop on Basic Research Needs for Superconductivity identified grand challenges and priorities for discovery and use inspired basic research to transform the US power grid to meet the needs of the 21st century. Vortex matter research is central to this endeavor and helps support both fundamental and applied research. The science of vortex matter embodies the fundamental mysteries of vortex-vortex interactions in an inhomogeneous and anisotropic matrix. Understanding the complex phase diagrams that result from these competing effects is an outstanding challenge. Simultaneously, the prospect of controlling these interactions has the potential for immediate impact on the emerging implementation of high temperature superconducting cables and opens new horizons for basic research such as the development of a microscopic theory for vortex dynamics and designs for pinning a vortex liquid at high temperatures. This presentation will highlight ways in which novel nanotechnology based methodologies, dynamic vortex creep phenomena and powerful computer simulations play a role in the high risk/high impact research which is expected to dramatically enhance our understanding of next-generation and new classes of superconductors.
4:30 PM - **M9.2
How Much Further Can We Increase the Critical Currents in YBa2Cu3O7 Films?
Leonardo Civale 1 , B. Maiorov 1 , S. Bailey 1 , H. Zhou 1 , F. Hunte 1 2 , I. Usov 1 , S. Foltyn 1 , T. Holesinger 1 , Q. Jia 1 , J. MacManus-Driscoll 3 , H. Wang 4
1 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 2 , Florida State University, Tallahassee, Florida, United States, 3 , Cambridge University, Cambridge United Kingdom, 4 , Texas A & M University, College Station, Texas, United States
Show Abstract5:00 PM - M9.3
Flux Pinning Enhancement in SmBCO Coated Conductor with Artificial Pinning Center.
Yutaka Yoshida 1 6 , Yusuke Ichino 1 6 , Masashi Miura 1 6 , Toshinori Ozaki 1 6 , Yoshiaki Takai 1 , Kaname Matsumoto 2 6 , Ataru Ichinose 3 6 , Masashi Mukaida 4 6 , Shigeru Horii 5 6 , Satoshi Awaji 7 , Kazuo Watanabe 7
1 Department of energy engineering and science, Nagoya university, Nagoya Japan, 6 , CREST-JST, Saitama Japan, 2 , Kyoto University, Kyouto Japan, 3 , CRIEPI, Yokosuka Japan, 4 , Kyushu University, Fukuoka Japan, 5 , University of Tokyo, Tokyo Japan, 7 , Tohoku university, Sendai Japan
Show Abstract5:15 PM - M9.4
Influence of Random and Correlated Disorder on the Critical Current of YBa2Cu3O7 Coated Conductors in Variable Lorentz Force Configuration.
Boris Maiorov 1 , H. Zhou 1 , S. Baily 1 2 , H. Wang 3 1 , J. MacManus-Driscoll 4 1 , T. Holesinger 1 , T. Haugan 5 , P. Barnes 5 , Q. Jia 1 , S. Foltyn 1 , L. Civale 1
1 MPA-STC, Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 2 MPA-NHMF, Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 3 Electrical and Computer Engineering, Texas A&M, College Station, Texas, United States, 4 Department of Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom, 5 , Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio, United States
Show AbstractMeasuring the angular dependence of the critical current density (Jc) is now a well-established technique to understand and characterize vortex pinning in coated conductors. Most of these studies, so far, were performed in the maximum Lorentz Force configuration (i.e., with the current I always flowing perpendicular to the applied magnetic field H). However, this is not the actual situation in most applications such as cables, inserts or motors, where the H and I are not always perpendicular one to each other. Here, we present angular and field Jc studies where the magnetic field is partially or totally aligned with the current, namely in a variable Lorentz force or force-free configuration, respectively. The effects on Jc of random, correlated and extended defects of YBa2Cu3O7 films grown on singles crystal or metal substrates is shown. The results are analyzed in terms of vortex pinning at different defects as well as taking into account vortex cut and recombination mechanism.
5:30 PM - M9.5
A Consideration of Pinning Mechanisms in Nanoparticulate Films.
Paul Barnes 1 , Chakrapani Varanasi 2 , Jack Burke 2 , Brandon Harrison 1 , Joseph Kell 1 , Timothy Haugan 1
1 AFRL/PRPG, Air Force Research Laboratory, Wright-Patterson AFB, Ohio, United States, 2 , University of Dayton Research Institute, Dayton, Ohio, United States
Show Abstract5:45 PM - M9.6
Nanotube Pores in YBa2Cu3O7-x Thick Films: Improved Single Vortex Pinning and Correlated Pinning.
Judy Wu 1 , Rose Lyn Emergo 1 , Xiang Wang 1 , Timothy Haugan 2 , Paul Barnes 2
1 Physics and Astronomy, University of Kansas, Lawrence, Kansas, United States, 2 , Air Force Research Laboratory (AFRL) , Wright-Patterson AFB, Ohio, United States
Show AbstractM10: Poster Session: Progress in High Temperature Superconductors II
Session Chairs
Brandon Harrison
Haiyan Wang
Thursday AM, April 12, 2007
Salon Level (Marriott)
9:00 PM - M10.1
YBa2Cu3O7-δ Formation by Processing of Laser-Ablated, Fluorine-Free Precursor Films
Kyunghoon Kim 1 , Yifei Zhang 1 , Roeland Feenstra 1 , Tolga Aytug 1 , Hans Christen 1 , Sylvester Cook 1 , Frederick List 1 , Jing Tao 1 , Stephen Pennycook 1 , Yuri Zuev 1 , David Christen 1
1 Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
Show Abstract The ex situ process for preparing YBCO films is attractive because high-quality, thick, dense and homogeneous coatings can be processed from post-deposition reaction of BaF2-containing precursors that can be deposited simply and inexpensively for coated conductor applications. However, the formation and removal of gaseous HF, due to the reaction of BaF2 with H2O, is problematic and can strongly affect the YBCO growth. The development of fluorine-free, environmentally stable PVD precursors would provide the benefits of processing without the need of water vapor or evolution of HF, thereby offering expanded possibilities for compatible buffer layers and simplified processing. The initial results were achieved from the deposition of 0.2 – 0.3 μm thick YBCO precursor films on single crystal LaAlO3 substrates by laser ablation from a ceramic F-free YBCO target. Typically, the depositions are conducted at room temperature in an O2 pressure of 1.0x10-4 Torr, with a laser energy density of 2 J/cm2. Analyses by XRD and ICP show that the precursors are amorphous or nanocrystalline, and composition is stoichiometric and nearly independent of background oxygen pressure. Following precursor deposition, in situ processing was done in the same deposition chamber by heating the samples to reaction temperatures of 750 - 850 C, in various gas ambients. To date, the best results are obtained by heating the precursor to temperature in an inert background, and then raising the oxygen pressure to the conversion point. Typical processing times are a few minutes, corresponding to minimum YBCO growth rates of ~1 nm/s. XRD analysis shows epitaxial growth and high crystallinity, although measured Tc values are somewhat suppressed at 88 K, with resulting critical current density, Jc of about 1 MA/cm2 at 77 K, as determined by magnetic hysteresis. The long-term oxygen annealing at 450 C in 1 atm of oxygen for 18 hours improved the Tc values (from 70 K to 88 K). The Z-contrast STEM images taken at different scales show that the F-free in situ processed YBCO film is nearly defect free. Of the few observable defects, most are planar intergrowths in the ~20 nm layer near the YBCO-substrate interface. There is improved perfection away from the interface, and virtually no threading defects through the film thickness can be observed. The lack of visible nanoscale defects is consistent with the difficulty in oxygen uptake and subsequent long-term oxygen annealing. In order to enhance the flux pinning, we report an approaches to introduce controlled defects. These approaches include deposition from doped YBCO targets (e.g. BZO) and deposition on substrate surfaces that have been pre-treated with nanoparticles.
9:00 PM - M10.10
Calorimetric Determination of AC Losses in High Temperature Superconducting Coils
David Blubaugh 1 , Paul Barnes 1 , John Murphy 2 , Timothy Haugan 1 , George Levin 2 , Chakrapani Varanasi 2
1 Propulsion Directorate , Air Force Research Laboratory, Wpafb , Ohio, United States, 2 , University of Dayton Research Institute, Dayton, Ohio, United States
Show AbstractHigh temperature superconductors (HTS), either as individual tapes or wound in coils, experience ac losses and generate heat when exposed to alternating currents or applied magnetic fields. Initial loss measurements at 77K will be provided for YBCO coils constructed using a 1 m and a 10 m length of YBCO coated conductor when an ac current is applied. The loss is determined using a new calorimetric system designed and constructed for this purpose in contrast to bolometric or electromagnetic means typically used to determine ac losses of HTS tapes. The system uses the standard nitrogen heat of vaporization method where the amount of heat released in the sample is determined by the change in nitrogen evaporation rate. The sensitivity of the system allows the measurement of power loss from a few milliwatts to a thousand milliwatts. As such, all thermal losses from the sample are taken into account and methods will be discussed to differentiate between various components of the total loss. In addition to the loss data, the details of the design and construction of this system will be presented along with the calibration data. The system can accommodate samples of various geometries such as linear tapes or coils of different sizes.
9:00 PM - M10.11
MgB2 Thin Films for Superconducting Electronics.
Yi Cui 1 , Ke Chen 1 , Qi Li 1 , Xiaoxing Xi 1 2
1 Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, United States, 2 Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States
Show Abstract9:00 PM - M10.12
Fabrication and Characterization of Superconducting MgB2 Bolometer.
Chiara Portesi 1 , Mauro Rajteri 1 , Riccardo Introzzi 1 , Emanuele Taralli 1 , Eugenio Monticone 1
1 , iNRiM, Torino Italy
Show Abstract9:00 PM - M10.14
Vortex Pinning in YBCO Thin Films Grown on Nanostructured Templates Prepared from Chemical Methods.
Marta Gibert Gutierrez 1 , P. Abellan 1 , F. Sandiumenge 1 , T. Puig 1 , X. Obradors 1
1 , Institut de Ciència de Materials de Barcelona ICMAB-CSIC, Bellaterra, Barcelona, Spain
Show Abstract9:00 PM - M10.15
Effect of RE/Ba Substitution Ratio on (Nd,Eu,Gd)Ba2Cu3Oy Films Fabricated by Low Temperature Growth Technique.
Yusuke Ichino 1 6 , Yutaka Yoshida 1 6 , Kouichi Inoue 1 , Yoshiaki Takai 1 , Kaname Matsumoto 2 6 , Masashi Mukaida 3 6 , Ataru Ichinose 4 6 , Shigeru Horii 5 6
1 Energy Engineering and Science, Nagoya University, Nagoya Japan, 6 CREST, Japan Science and Technology Agency, Kawaguchi Japan, 2 Materials Science and Engineering, Kyoto University, Kyoto Japan, 3 Materials Science and Engineering, Kyushu University, Fukuoka Japan, 4 , Central Research Institute of Electric Power Industry, Yokosuka Japan, 5 Applied Chemistry, University of Tokyo, Tokyo Japan
Show Abstract9:00 PM - M10.16
The Field-angular-dependence of Coated Conductor Performance.
Noel Rutter 1 , Marcus Weigand 1 , John Durrell 1
1 Materials Science, University of Cambridge, Cambridge United Kingdom
Show Abstract9:00 PM - M10.17
An Empirical Consideration of the Critical Current Density as a Function of Temperature.
Paul Barnes 1 , Brandon Harrison 1 , Joseph Kell 1 , Timothy Haugan 1 , Michael Sumption 2
1 AFRL/PRPG, Air Force Research Laboratory, Wright-Patterson AFB, Ohio, United States, 2 , The Ohio State University, Columbus, Ohio, United States
Show Abstract9:00 PM - M10.2
Thickness Dependence of Orientation and Superconducting Properties of YBa2Cu3Oy Thick Films Fabricated by Low Temperature Growth Technique.
Shuhei Funaki 1 6 , Yutaka Yoshida 1 6 , Yusuke Ichino 1 6 , Masashi Miura 1 6 , Yoshiaki Takai 1 , Kaname Matsumoto 2 6 , Ataru Ichinose 3 6 , Masashi Mukaida 4 6 , Sigeru Horii 5 6
1 Energy Engineering and Science, Nagoya University, Nagoya Japan, 6 , CREST-JST, Saitama Japan, 2 Materials Science and Engineering, Kyoto University, Kyoto Japan, 3 , Central Research Institute of Electric Power industry, Kanagawa Japan, 4 Materials Science and Engineering, Kyushu University, Fukuoka Japan, 5 Applied Chemistry, University of Tokyo, Tokyo Japan
Show Abstract9:00 PM - M10.3
Depth Profiling Resonant Raman Spectrometry On YBa2Cu3O7-δ Films.
Maria Branescu 1 , Coralie Naudin 2 , Arturas Vailionis 3 , Ian Ward 4
1 , NATIONAL INSTITUTE OF MATERIALS PHYSICS, Bucharest Romania, 2 , Horiba Jobin Yvon, 59650 Villeneuve d'Ascq France, 3 , Stanford University, Palo Alto 95305, California, United States, 4 , EAG, Sunnyvale 94086, California, United States
Show Abstract9:00 PM - M10.4
Correlation of YBCO Film Quality to Magnetic Susceptibility Measurements
B. Harrison 1 , Paul Barnes 1 , Michael Sumption 2 , Joseph Kell 1 , Iman Maartense 1 , Timothy Peterson 1 , Timothy Haugan 1
1 Propulsion Directorate, Air Force Research Laboratory, Wpafb, Ohio, United States, 2 Department of Materials Science and Engineering, Ohio State University, Columbus, Ohio, United States
Show Abstract9:00 PM - M10.5
New Operating Modes of Scanning Laser Microscopy.
Ryan James 1 , Jeremy Young 1 , Megumi Yamamoto 1 , Chuhee Kwon 1 , George Levin 2 , Timothy Haugan 2 , Paul Barnes 2
1 Physics and Astronomy, California State University Long Beach, Long Beach, California, United States, 2 , Air Force Research Laboratory, WPAFB, Ohio, United States
Show Abstract9:00 PM - M10.6
Spatial Dissipation Length and Local Jc Estimation in YBCO Coated Conductor Multi-filaments Using Low Temperature Scanning Laser Microscope.
Zulistiana Zulkifli 1 , Takashi Fujiwara 1 , Tomoyo Nakamura 1 , Takanobu Kiss 1 , Keiji Enpuku 2 , Naoji Kashima 3 , Masami Mori 3 , Shigeo Nagaya 3 , Akira Ibi 4 , Yutaka Yamada 4 , Yuh Shiohara 4
1 Department of Electrical and Electronic Systems Engineering, Kyushu University, Fukuoka Japan, 2 Department of Superconductivity, Kyushu University, Fukuoka Japan, 3 , Chubu Electric Power Co., Inc. , Nagoya Japan, 4 Superconductivity Research Laboratory, International Superconductor Technology Center, Tokyo Japan
Show AbstractCurrent flow in High temperature superconductor (HTS) coated conductor (CC) has been shown to become non-uniform due to the presence of disordered microstructures having several μm in size. In this study we used low temperature scanning laser microscope (LTSLM) to investigate the local dissipation of the flux flow due to microstructural inhomogeneity in YBCO CC in a multi-filament structure. The 2D scanning laser induced local heating giving a voltage response (ΔV) at the local coordinate. In the bias current dependence of flux flow dissipation at a fixed temperature, percolative behavior of the dissipations is observed. Statistical analysis of the 2D images of the dissipation also enabled us to estimate spatial length scale between dissipation occurrences; estimated space is of 170μm. By combining the dissipation information with current density distribution obtained from the Scanning SQUID Microscopy (SSM), we estimated local Jc distribution in the multi-filament structure. By applying this technique, we succeeded to visualize local variation of the Jc values within the multi-filament. This work was partly supported by the New Energy and Industrial Technology Development Organization (NEDO) as Collaborative Research and Development of Fundamental Technologies for Superconductivity Applications and also supported by JSPS: KAKENHI (18360153).
9:00 PM - M10.8
Coils of GdBCO and YBCO.
Hiroyuki Fukushima 1
1 , ISTEC-SRL NCCC, Nagoya, Aichi, Japan
Show AbstractWe developed a 60 m long GdBCO coated conductor and a 212m long YBCO coated conductor. Each coated conductor exhibited a high Ic value of 183 A and 245 A at 77 K, respectively. For evaluation of the properties of long GdBCO coated conductor and long YBCO coated conductor, we have made two solenoid coils using each of them. The measured value of a central magnetic field in GdBCO coil was 0.48 T, 1.2 T and 5.7 T at 77 K, 64 K and 4.2 K, respectively. The measured value of a central magnetic field in YBCO coil was 0.68 T at 77 K. The values of a critical current and the central magnetic field in these coils correspond to the calculated one using each Jc -B property. We can easily measure the value of a critical current of a long coated conductor by making coil.This work was supported by the New Energy and Industrial Technology Development Organization (NEDO) as Collaborative Research and Development Fundamental Technologies for Superconductivity Applications.
9:00 PM - M10.9
The Basic Energy Sciences Workshop on Basic Research Needs for Superconductivity
James Horwitz 1 , John Sarrao 2 , Wai-Kwong Kwok 3
1 Basic Energy Sciences, Department of Energy, Germantown, Maryland, United States, 2 Materials Physics & Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 3 Materials Science Division, Argonne National Laboratory, Argonne, Illinois, United States
Show AbstractElectricity is the mainstay of our energy distribution system, providing instant power for light, refrigeration, industry, transportation, communication, and digital electronics at the flick of a switch. Demand for electricity will grow by 50% in the US and 100% in the world by 2030. Yet the electricity delivery system is threatened by increasingly inadequate capacity, reliability, and power quality in urban areas where power density and demand growth are highest. Superconductivity can transform urban electricity delivery through cables with five times the capacity of copper wires, smart, self-healing fault current limiters and reactive power controllers that instantaneously react to current, voltage and phase angle events, and small, robust transformers that use no contaminating or flammable oil and are safe for urban areas. The Basic Energy Sciences Workshop on Basic Research Needs for Superconductivity examined the current status and future prospects of superconductivity to transform the power grid to meet the needs of the 21st century. Its report (http://www.sc.doe.gov/bes/reports/files/SC_rpt.pdf ) outlines the grand challenges of the field and the high risk-high payoff research directions that are capable of overcoming them. This poster will present the Workshop Report, including the gaps between present performance and future needs, the transformational potential of superconductivity to overcome them, and the priority research directions that are capable of achieving the transformation.
Symposium Organizers
Paul Barnes Air Force Research Laboratory
Dominic Lee Oak Ridge National Laboratory
Chan Park Seoul National University
Naoyuki Amemiya Yokohama National University
Jodi Reeves SuperPower, Inc.
M11: Low Frequency AC Losses in YBCO Coated Conductors
Session Chairs
Masaki Suenaga
Michael Sumption
Thursday AM, April 12, 2007
Room 3024 (Moscone West)
9:30 AM - **M11.1
External Field and Transport Loss in YBCO Coated Conductors and MgB2 at 50-200 Hz; Influence of Magnetic Components
Mike Sumption 1 , Milan Majoros 1 , E. Collings 1
1 Material Science , Ohio State, Columbus, Ohio, United States
Show AbstractAC loss measurements have been made on YBCO coated conductors and MgB2 multifilamentary strands under external field and transport loss conditions. Externally applied field loss was measured as a function of sinusoidal AC field amplitude using the pick-up coil method at frequencies from 50-200 Hz. 2G conductors with various levels of Cu stabilizer were measured and the eddy current contribution from these were extracted. Striped conductors were measured and the results show the relative effectiveness of filamentarization, which is dependent upon both ramp rate and filament inter-connectedness. Transport current loss was measured for unfilamented conductors and the loss was seen to be closer to the cube-law variant of the Norris equations. This deviation from the expected fourth-power loss was attributed to both contributions from the mildly magnetic substrate, and to self-field effects. The influence of mildly magnetic components in the sheaths of MgB2 conductors was also noted, and the effects were quite large in transport current conditions. Comparisons of loss limitations in YBCO and MgB2 are discussed.
10:00 AM - M11.2
AC Current Driven Vortex Dynamics in YBCO Thin Films and Coated Conductors.
Andrea Lucarelli 1 , Ran Yang 1 , Gunter Luepke 1 , George Levin 2 , Timothy Haugan 2 , Paul Barnes 2 , Francesco Grilli 3
1 Applied Science, College of William and Mary, Williamsburg, Virginia, United States, 2 Power Generation Branch, Air Force Research Laboratory, Wright-Patterson AFB, Ohio, United States, 3 Superconductivity Technology Centre, Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show Abstract10:15 AM - M11.3
Magneto-Optical Imaging of Magnetic Flux Profile of YBa2Cu3O7 Films on a Magnetic Substrate
Masaki Suenaga 1 , Zu-Xin Ye 1 , Qiang Li 1
1 Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York, United States
Show Abstractac losses of YBa2Cu3O7 films on a magnetic substrate were substantially reduced from those of the film on a non-magnetic substrate in perpendicular magnetic fields. [M. Suenaga and Q. Li, Appl. Phys. Lett. 88, 262501 (2006).] This result was explained by assuming the changes in magnetic field profiles of the film by the magnetic substrate from those of the film on a non-magnetic substrate. In order to confirm the above assumption and to further investigate the profiles in detail, the flux density profiles of YBCO films on a magnetic substrate as well as those of the substrate were investigated by a magneto-optical imaging technique for variously shaped YBCO films on a Ni-W substrate at various temperatures. It was found that the magnetic profiles of a YBCO strip on a magnetic substrate was similar to those for a superconducting slab in parallel magnetic fields instead of sharply enhanced flux at the edges of the films for the film on a non-magnetic substrate. Also, the flux patterns of the substrate were strongly influenced by the flux profiles of the superconductor. These observations at different temperatures and their implications to the magnetic properties of superconducting films will be discussed.This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CHI-886 with the U. S. Department of Energy. * Present address: Department, Texas A&M University, College Station, TX.
10:30 AM - M11.4
Transport AC Losses of YBCO Coated Conductor Coils.
Francesco Grilli 1 , Stephen Ashworth 1
1 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show Abstract10:45 AM - M11.5
Copper Stabilized Multifilament Coated Conductors
George Levin 1 , Paul Barnes 2 , Michael Sumption 3
1 , University of Dayton Research Institute, Dayton, Ohio, United States, 2 Propulsion Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base , Ohio, United States, 3 Department of Material Science and Engineering, Ohio State University, Columbus, Ohio, United States
Show AbstractWe report the data on magnetization losses and critical current in experimental multifilament copper stabilized coated conductor. A 4 mm wide and 4 cm long copper stabilized samples of coated conductor were subdivided into eight to ten 0.5-0.4 mm wide filaments by laser micromachining and subjected to post-ablation treatment. As the result, each superconducting filament is covered by a stabilizing copper layer, but the filaments are insulated from the substrate and from each other. The hysteresis loss is reduced in proportion to the width of the filaments. The coupling loss is also small in the range of the sweep rate up to 20 T/s. The economic feasibility of laser micromachining for coated conductors will be discussed.
11:00 AM - M11.6
Fabrication and Characterization of Ag-Bi2223 Tapes with Resistive Barriers for Reduction in AC Losses.
Akio Oota 1 , Yohei Fukumoto 1 , Taeko Yasunami 1 , Ryoji Inada 1 , Yuichi Nakamura 1 , Pingxiang Zhang 2
1 Electrical and Electronic Engn., Toyohashi Univ. Tech., Toyohashi Japan, 2 , Northwest Institute for Nonferrous Metal Research, Xi'an China
Show AbstractReduction in AC losses for Ag-sheathed Bi2223 tapes is one of the key issues for practical power applications such as power cables or transformers. The large loss generation in the tapes under AC operation is mainly attributed to a strong electromagnetic coupling among the Bi2223 filaments due to low matrix resistivity of Ag and also to a direct bridging among the filaments. An introduction of interfilamentary resistive barriers combined with filament twisting with an appropriate pitch is necessary to suppress the electromagnetic coupling and/or the bridging among the filaments so that it reduces the AC losses under external AC magnetic field. We use the insulating oxides of CuO, Cu2O and Ca2CuO3 as barrier materials for tape fabrication by a powder-in-tube method. These oxides were coated with the slurry on all surfaces of the hexagonal monocore wires. Subsequently, several pieces of the coated wires were packed into another Ag-tube, and the composites were deformed into tape shape. The transverse resistivity and AC loss properties under external AC magnetic field for the barrier tape are examined and compared with those for the tape without the barriers. The fabrication of the barrier tapes on the order of several meters is also reported, together with the uniformity of superconducting properties along a tape length.This work was supported in part by Grant-in-Aids for Scientific Research (No. 17206026) from the Japanese Society of the promotion of science, and also by that (No. 17760233) from the Ministry of Education, Culture, Sports, Science and Technology.
11:15 AM - M11: ac loss
BREAK
M12: Diagnostics, Grain Boundaries, and Properties of HTS Conductors
Session Chairs
Bernhard Holzapfel
Winnie Wong-Ng
Thursday PM, April 12, 2007
Room 3024 (Moscone West)
11:30 AM - **M12.1
Current Carrying Properties in YBCO Coated Conductors under the Influence of Current Blocking Obstacles and Grain Boundaries
Takanobu Kiss 1 , Masayoshi Inoue 1 , Tomoya Nakamura 1 , Arkadiy Matsekh 1 , Daisuke Mitsui 1 , Takshi Fujiwara 1 , Zulistiana Zulkifli 1 , Kazutaka Imamura 1 , Akira Ibi 2 , Yutaka Yamada 2 , Naoji Kashima 3 , Masami Mori 3 , Shigeo Nagaya 3 , Takeharu Kato 4 , Tsukasa Hirayama 4 , Yuh Shiohara 5 2
1 Electrical and Electronic Systems Engineering, Kyushu University, Fukuoka Japan, 2 Nagoya Coated Conductor Center, Superconductivity Research laboratory, Nagoya Japan, 3 , Chubu Electric Power Co., Nagoya Japan, 4 , Japan Fine Ceramics Center, Nagoya Japan, 5 Division of Superconducting Tape and Wire, Superconductivity Research Laboratory, Tokyo Japan
Show AbstractUsing novel characterization techniques such as thermal laser stimulation and scanning SQUID microscopy (SSM), we have carried out spatially resolved measurements on 1) local flux flow dissipation under external magnetic field, 2) defects and grain boundaries in YBCO layers and 3) local current flow in the coated conductors. Influence of current blocking obstacles and grain boundaries has been visualized under external magnetic field up to 5T. AC flow in a multifilamentary structure has also been visualized by the SSM. Combination of those three measurements leads deep insights into current limiting mechanism in the coated conductors. Crossover from inter-grain Jc to the intra-grain Jc has been visualized clearly at an artificial grain boundary (GB). Influence of current blocking obstacles and GBs becomes moderate under high external fields though those mechanisms are different: smaller n-index, crossover at GB, respectively. Those measurements are also effectively feed back to improve process conditions to get better uniformity. This work was supported by the New Energy and Industrial Technology Development Organization (NEDO) as Collaborative Research and Development of Fundamental Technologies for Superconductivity Applications.
12:00 PM - M12.2
Imaging the Dissipation at the Micrometer Scale as a Function of Magnetic Field in Coated Conductors.
Dmytro Abraimov 1 , Matthew Feldmann 2 , Alex Gurevich 1 , David Larbalestier 1
1 Applied Superconductivity Center, National High Magnetic Field Laboratory, Tallahassee, Florida, United States, 2 Applied Superconductivity Center, University of Wisconsin, Madison, Madison, Wisconsin, United States
Show Abstract12:15 PM - M12.3
Sub-gap Structures and Local Inhomogeneity in YBCO Films on Bicrystal Substrates.
Chuhee Kwon 1 , Megumi Yamamoto 1 , Ryan James 1 , Jeremy Young 1 , Timothy Haugan 2 , Paul Barnes 2
1 Physics and Astronomy, California State University Long Beach, Long Beach, California, United States, 2 , Air Force Research Laboratory, WPAFB, Ohio, United States
Show Abstract12:30 PM - M12.4
Key Microstructural Features of YBa2Cu3O7-∂ Films Made by MOCVD
Terry Holesinger 1 , Boris Maiorov 1 , James Coulter 1 , Leonardo Civale 1 , Stephen Foltyn 1 , Yimin Chen 2 , Venkat Selvamanickam 2
1 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 2 , SuperPower, Inc., Schenectady, New York, United States
Show AbstractMetal organic chemical vapor deposition (MOCVD) has been shown to produce high critical current densities (Jc) in YBCO coated conductors. The characteristic defect structures of the high-current (Ic > 500 A/cm-w) MOCVD films are discussed within the context of connecting key microstructural features with the properties of these high performance coated conductors. Analytical electron microscopy was used to clearly identify the overall structure, key defect structures for providing pinning centers, and defects that could limit the growth of thick MOCVD films for high current applications.
M13: REBCO Superconductors and Flux Pinning Mechanisms
Session Chairs
Thursday PM, April 12, 2007
Room 3024 (Moscone West)
2:30 PM - **M13.1
Phase Equilibria for the Ba-R-Cu-O (R=Y and Lanthanides) Coated-Conductor Research.
Winnie Wong-Ng 1 , Lawrence Cook 1 , Zhi Yang 1 , Igor Levin 1 , Makoto Otani 1 , Peter Schenck 1 , Joseph Ritter 1 , Mark Vaudin 1 , Ron Feenstra 2 , Terry Holesinger 3 , Amit Goyal 2 , Timothy Haugan 4 , Paul Barnes 4
1 Ceramics, NIST, Gaithersburg, Maryland, United States, 2 Materials Science and Technology, ORNL, Oak Ridge, Tennessee, United States, 3 Materials Science and Technology, LANL, Los Alamos, New Mexico, United States, 4 Power Generation Branch, AFRL, Wright-Patterson AFB, Ohio, United States
Show AbstractA wide variety of large-scale industrial applications based on the continuing advancement of the coated conductor technology are potentially possible in the near future. Important applications include power distribution, energy storage, and advanced motors and magnets. To implement these applications, the availability of low-cost, long-length, and high performance wire/tape and cable is critical. Phase diagrams are commonly regarded as “blue prints” for the optimization of processing. We have focused our efforts on phase equilibria studies of Ba2RCu3O6+x (R=lanthanides and Y) for coated conductor applications. This talk will highlight our results in three related areas: (i) phase diagrams for the BaO-R2O3-CuOx (R=Nd, Sm, Eu, Gd, Ho, Y, Er, Tm and Yb) systems under atmospheric-controlled conditions to match those used in coated conductor processing. A comparison of these phase diagrams will be discussed; (ii) high-temperature x-ray diffraction (HTXRD) and transmission electron microscopy (TEM) experiments. These experiments were conducted to determine phase evolution mechanisms of the superconducting Ba2YCu3Ox and Ba2RCu3Ox phases and phase relations in the Ba-Y-Cu-O and Ba-R-Cu-O films prepared by the ex situ BaF2 process and the trifluoroacetic acid (TFA) solution technique. A comparison of the phase relations in films and in the corresponding bulk systems will be discussed; (3) solid solution of the Ba2-x(Nd1+x-yRy)Cu3O6+z (R=Gd, Y and Yb) and the Ba2-x(R1+x-yYy)Cu3O6+z (R=Eu and Sm) systems for potential flux-pinning applications.
3:00 PM - **M13.2
Understanding Jc versus thickness Relation Through Defect Structure analysis of <300 nm thick EuBa2Cu3O7-x thin films
Judith MacManus-Driscoll 1 , Meicheng Li 1 , Stuart Wimbush 1 , Ahmed Kursumovic 1 , Mary Vickers 1 , Quanxi Jia 2 , Boris Maiorov 2 , Leonardo Civale 2 , Steve Foltyn 2 , Haiyan Wang 3
1 Department of Materials Science and Metallurgy, , University of Cambridge, Cambridge United Kingdom, 2 Superconductivity Technology Centre, Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 3 , Texas A&M, , Houston, Texas, United States
Show AbstractThe type and density of defects (dislocations and non-uniform strain) in <300 nm thick EuBa2Cu3O7-x (Eu- 123) films grown on YBCO buffered SrTiO3 (STO) substrates were analyzed using high resolution X-ray diffraction. Eu-123 films rather than YBa2Cu3O7-x films were studied because they are smooth and allow sufficiently high x-ray intensities for quantitative analysis. The films were strongly distorted for < 100 nm thickness. The mosaic structure was characterized by means of tilt and twist angles between the mosaic sub-grains. The mosaicity was correlated with the densities of screw and edge type dislocations, respectively. There is a sharp decrease in defect density with thickness which correlates directly with a decrease in low field Jc. The results indicate that lattice mismatch strain between coated conductor layers and substrates, interlayers and/or particles should be maximized for enhancing Jc.
3:30 PM - M13.3
Flux Pinning Enhancement of YBCO Films by Rare Earth Doping at Minute Concentrations
B. Harrison 1 , Joseph Kell 1 , Paul Barnes 1 , Haiyan Wang 3 , Timothy Haugan 1 , Chakrapani Varanasi 2 1 , Manisha Rane 4 , Frank Ramos 4
1 Propulsion Directorate, Air Force Research Laboratory, Wpafb, Ohio, United States, 3 Department of Electrical and Computer Engineering, Texas A & M University, College Station, Texas, United States, 2 , University of Dayton Research Institute, Dayton, Ohio, United States, 4 , Albany State University, Albany, New York, United States
Show Abstract3:45 PM - M13.4
Evolution of Pinning Mechanisms with Growth Temperature in YBa2Cu3O7-x Thin Films Grown by Pulsed Laser Deposition.
Zhijun Chen 1 2 , Sang IL Kim 1 2 , Fumitake Kametani 1 , Alex Gurevich 1 , David Larbalestier 1 , Kyoung Jin Choi 2 , Ho Wan Jang 2 , Chang-Beom Eom 2
1 Applied Superconductivity Center, National High Magnetic Field Laboratory, Tallahassee, Florida, United States, 2 , University of Wisconsin - Madison, Madison, Wisconsin, United States
Show Abstract4:00 PM - M13.5
The Effect of Dy on the Structure of YBa2Cu3O7 Coated Conductors
Miriam Herrera Collado 1 , Volkan Ortalan 1 , David Morgan 2 , Nigel Browning 1 3 , Martin Rupich 4
1 Department of Chemical Engineering and Materials Science, University of California at Davis, Davis, California, United States, 2 Department of Molecular and Cellular Biology, University of California at Davis, Davis, California, United States, 3 Chemistry, Materials and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States, 4 , American Superconductor Corporation, Westborough, Massachusetts, United States
Show AbstractThe high critical current density (Jc) of the superconducting compound YBa2Cu3O7-x (Y123) makes it a serious candidate for widespread technological applications, such as microwave filters, resonant cavities or coated conductor wire technologies for power applications. In order to enhance the Jc of this superconductor in high magnetic fields, chemical doping can be used to produce nanometre-size defects or second phases that can act as pinning centres. For this method to be effective, the size of the defect should be of the order of the coherence length of Y123 and the chemical dopant should have a benign effect on the transport properties of Y123. For these two reasons, rare-earth (RE) ions in the form of metal-organic complexes are often chosen to be added to the precursor solutions during metal organic deposition. In this work, we have investigated the structural effect of doping Y123 epitaxial layers with Dy using advanced imaging and analysis techniques in the Scanning Transmission Electron Microscope (STEM). The studied samples consist of a 800nm thick Y123 layer doped with Dy (50% in a molar basis) grown on a cube-textured NiW(5%) alloy substrate buffered with oxide layers 75nm thick with the structure CeO2/YSZ/Y2O3/NiW (where YSZ = Y stabilized Zirconia). Energy Dispersive X-ray Spectroscopy (EDS) has revealed that the addition of Dy to Y123 causes the substitution of Y by the RE atoms, giving rise to a compound of formula (YzDy1-z)Ba2Cu3O7-x, with z~0.5. The addition of Dy also introduces a second phase in the layer, forming particles with average size 20-30nm (although also some bigger ones with size of around 150nm have been observed). Preliminary analyses of these particles by EDS suggests that their composition is (YsDy1-s)2Cu2O5, with s~0.6. Moreover, 3-dimensional (3D) studies of these particles by High Angle Annular Dark Field (HAADF) STEM tomography has permitted the determination of the shape of the particles and their distribution throughout the Y(Dy)123 layer. This information is of extraordinary technological importance, given that the capability of these inclusions for the flux pinning in the superconducting compound is strongly related to these properties of the particles. The effect of the size, shape, and distribution of the secondary phases within the structure on flux pinning will be discussed.
4:15 PM - M13: Pin4
BREAK
M14: Deposition Processes for High Performance HTS
Session Chairs
Thursday PM, April 12, 2007
Room 3024 (Moscone West)
4:30 PM - **M14.1
Exploring Low Cost High Performance Coated Conductor Processes Using Liquid Assisted Growth.
R. Hammond 1 , Gertjin Koster 1 , M. Beasley 1 , T. Geballe 1
1 Geballe Lab for Adv Materials, Stanford University, Stanford, California, United States
Show AbstractTwo recent surveys set the agenda for future requirements for Coated Conductors to meet the performance and cost goals for utility implantation. Both surveys seem to say that present processes are not likely to meet these goals soon. The BES-DOE report determines that the Jc (H, T) has to be 5 to 10 times higher than the currently best Jc, and for some applications this must be the case at magnetic fields of 3 – 5 T. The “Market Readiness Review” (Navigant) survey of utility customers determined that the cost must be factors of 10-100 lower before a sizable market can develop. Improving the performance with higher Jc will of course reduce the cost to performance (C/P) ratio as well.We will review our process that promises to have a high throughput at low cost. The YBCO (or REBCO) is deposited at near room temperature by various means---for research studies PLD is being used (1), and for large area and high rate electron beam co-deposition is being used. The amorphous precursor is then reacted in the P(O)—T region of the YBCO and liquid Ba-Cu-O stability diagram. The growth of the YBCO is very rapid—seconds to minutes. Generally the morphology is almost perfect c-axis with no defects (as shown by Z-contrast STEM at ORNL). This defect free and very rapid growth is a result of liquid assisted nucleation and growth.The challenge next will be to introduce controlled defects into this very fast process. This is being approached by collaboration with ORNL (talk this session) and LANL using various schemes, including co-evaporated BZO. We are also exploring the Sm123 with Sm substitution on the Ba sites to induce a composition modulation that has shown excellent pinning at high magnetic fields (2).(1). Kim et al, this session.(2). Y. Yoshida, K. Matsumoto et al., Jpn. J. Appl. Phys., 44, L546-L548, 2005.
5:00 PM - M14.2
Reactive Co-Evaporation of YBCO for 2G HTS Tapes.
Jonathan Storer 1 , Chris Sheehan 1 , Vlad Matias 1 , Jens Hanisch 1 , Yates Coulter 1
1 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show Abstract5:15 PM - M14.3
Nonlinear Nonlocal Meissner effect in YBCO.
Dan Agassi 1 , Dan Oates 2 , K. Irgmaier 3 , Edmond Wong 4 , Anna Leese-deEscobar 4
1 , Naval Surface Warfare Center, Carderock Division, West Bethesda, Maryland, United States, 2 , M.I.T. Lincoln Laboratory, Lexington, Michigan, United States, 3 , THEVA Dünnschichttechnik GmbH, Ismaning Germany, 4 , SPAWAR Systems Center, San Diego, California, United States
Show Abstract5:30 PM - M14.4
Critical Currents in Magnetic Field of Co-evaporated YBCO Coated Conductor Samples on a Variety of Substrates.
Jens Haenisch 1 , Yates Coulter 1 , Chris Sheehan 1 , Storer Jonathan 1 , Vladimir Matias 1
1 STC-MPA, Los Alamos National Lab, Los Alamos, New Mexico, United States
Show AbstractYBCO films with a thickness of up to 5 µm are prepared by reactive coevaporation on technical substrates (i.e. IBAD and RABiTS templates). Four films, 7 cm long, can be processed simultaneously in one deposition run. The temperature during the deposition is extremely stable due to the black-body radiation heater design and the sample holder rotation inside the heater is fast compared to deposition rate fluctuations. This offers the possibility to study the influence of different substrates or the YBCO film thickness on the superconducting properties. Direct comparison of films with exactly the same deposition conditions on different substrates is possible with our method. By varying the structural parameters of the IBAD-MgO layer, such as in- and out-of-plane texture and c-axis tilt with respect to the tape normal, we investigate their influence on the transport properties in applied magnetic fields up to 7 T. We use the angular dependence of the critical current in a magnetic field to elucidate the nature of pinning in these samples. We also present data on Jc-thickness dependence for co-evaporated films in a variety of magnetic field configurations.
5:45 PM - M14.5
Control of Particulate Size During Pulsed Electron Deposition.
John Mathis 1 , Hans Christen 2
1 Physical Sciences, Embry-Riddle University, Daytona Beach, Florida, United States, 2 Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
Show AbstractPulsed electron deposition (PED) has recently become an attractive alternative to pulsed laser deposition (PLD) for growing thin films because of PED’s relatively low cost. A potential problem with PED, however, is the generation of particulates which interfere with film growth. The influence of ambient pressure and accelerating potential on the number of and size of particulates appearing on the surface of films was investigated for the barium fluoride-based YBCO precursor process. The size of the particulates varies exponentially with accelerating voltage. The size of the particulates can also be reduced to less than 100 nm by increasing the ambient pressure beyond that required for optimum deposition rate. The ability to control the size of particulates could make PED useful for technical applications where the generation of sub-micron sized materials is desired.