Microstructure and Transport Properties of Oxide Superconductors
Microstructural control is crucial to improve transport critical current density in oxide superconductors. Bulk sintered materials contain a number of defects such as porosities, second phases, cracks, impurities, variation in chemical composition and other grain boundary defects. All these defects reduce critical current density of oxide superconductors. The number of these defects can be minimized by controlling the processing conditions. However we have found that the weak-link effects cannot be completely eliminated from the material as far as we employ the solid state reaction. This is confirmed by a sharp degradation of Jc in magnetic field. No sample size dependence in magnetization hysteresis between the increasing and decreasing magnetic field process also indicates that supercurrent localizes intragranularly.
The weak-link problems can be overcome by employing the carefully controlled solidification process. In such solidified samples, magnetic field dependence of transport critical current density was quite small compared with that of bulk sintered material and Jc value exceeding 1000 A/cm2 was obtained at 77K in 10 T.
KeywordsCritical Current Density Magnetization Hysteresis Superconducting Phase Magnetic Field Dependence Oxide Superconductor
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- M. Murakami, Paper presented at Fifth Japan-US Workshop on High-field suerconducting material and standard procedures for high field superconducting materials testing held in Fukuoka, 165 (1987).Google Scholar
- M. Murakami, M. Morita, K. Sawano, T. Inuzuka, S. Matsuda and H. Kubo, Proceedings of SINTERING ’87 held in Tokyo in 1987, ed. by S. Somiya.Google Scholar
- M. Murakami, H. Teshima, M. Morita, K. Doi, S. Matsuda, H. Hamada, M Fujinami, M. Saga, M. Sugiyama and M. Nagumo, Proceedings of MRS Meeting held in Tokyo (1988).Google Scholar
- M. Murakami and M. Morita, Proceedings of MRS Meeting held in Tokyo (1988).Google Scholar