2002 Fiscal Year Final Research Report Summary
Electronic Structure of Homo-phase Grain Boundaries and Correlated Percolation -Fundamental Understanding of Transport Property and Nano-scale Microstructure Control of Composite Superconductors-
| Project/Area Number |
13305045
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical properties of metals
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
OSAMURA Kozo KYOTO UNIVERSITY, Division of Engineering, Professor, 工学研究科, 教授 (50026209)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAI Akira KYOTO UNIVERSITY, Division of Engineering, Professor, 工学研究科, 教授 (80143543)
MATSUMOTO Kaname KYOTO UNIVERSITY, Division of Engineering, Assistant Professor, 工学研究科, 助教授 (10324659)
KUROKAWA Syu KYOTO UNIVERSITY, Division of Engineering, Assistant, 工学研究科, 助手 (90303859)
ADACHI Hiroki KYOTO UNIVERSITY, Division of Engineering, Assistant, 工学研究科, 助手 (00335192)
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| Project Period (FY) |
2001 – 2002
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| Keywords | High-temperature superconductor / Y123 / Bi2223 / Critical current density / Superconductivity mechanism / Pinning / Percolation / Weibull analysis |
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| Research Abstract |
1.Sample preparation and microstructure observation : in order to make clear the degree of texturing, the polycrystalline Bi2223 films were prepared on the textured Ag substrate, Mg0 or SrTi03 single crystal. The crystal orientation was investigated by means of EBSP and the microstructural features of grain boundaries have been precisely analyzed by using SEM and EPMA. The crystal growth technique to prepare the [0011 oriented Bi2223 film with 1 micron-meter was established.
2.Measurement and analysis of critical currents : the current - voltage relationship has been investigated at the micro-area by using the patterned samples. Its angular dependence of magnetic field and the strain dependence in Y123 thin films were precisely measured. The temperature dependence of critical current was measured in Bi2223 films. Their experimental data were applied to Weibull analysis. The high performance Bi2223 thin film with critical current density higher than 1 MA/m2 at 77 K has been developed.
3.A
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nalysis of critical current of Bi2223 tape by using Weak Link Path model : the optimum percolation path in the sample has been estimated based on the model. The J-E curve obtained by computer simulation was compared with the experimental data. From the comparison, some microstructure factors like (a) current concentration, (b) clustering of non-SC links, (c) distribution of non-SC clusters have been elucidated.
4.Improvement of transport property in the polycrystalline samples based on the Weak Link Path model : the optimization of transport properties was considered from the theoretical calculation based on the model. As a result, the microstructure model to realized the optimum property in Bi2223 tapes was proposed, where the grain boundary weak link limits the critical current.
5.Mechanical property and its influence to critical current in Bi2223 tapes : the mechanical property of Bi2223 tapes was analyzed based on the rule of mixture by taking into consideration about the thermal residual stress. The true stress exerted on the SC oxide layer was made clear. In the stress region up to 60 MPa, the critical current reversibly decreased with increasing stress. This phenomenon was attributed to the SNS junction of the weak link at homo-phase grain boundaries. Less
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Research Products
(12 results)
