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High-temperature superconducting ceramics: Processing-related issues and the thermodynamics of the phase transition

Thesis/Dissertation ·
OSTI ID:5399000
Various processing techniques were used to fabricate YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} and YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}-metal composites. First superconducting particulate composites were fabricated using powder-metallurgy and liquid-phase-sintering techniques. Composites were fabricated with Ni, Cu, and Sn. The processing conditions required to fabricate these composites were investigated in detail. It was found that the contacts between individual ceramic grains controlled the transport behavior of polycrystalline 123. Various methods, including the effect of additives (Ag/Ag{sub 2}O) were investigated to reduce this contract or weak-link problem. As the field progressed, it was established that misalignment between adjacent grains in polycrystalline 123 drastically reduces the critical current density J{sub c}. In view of this, melt-processing techniques were used to fabricate to highly aligned 123 and 123/Ag composites. In addition to processing studies, a classical thermodynamical analysis across the superconducting transition to study the variation of physical quantities across the transition was conducted.
Research Organization:
Rochester Univ., NY (United States)
OSTI ID:
5399000
Country of Publication:
United States
Language:
English