I Ba2Cu3Oyの超電導特性におよぼす長時間焼結の影響

概要

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Y Ba 2Cu3Oy powders obtained by pulverizing the mixed powder aggregate fired at 1173K for 86.4ks were cold pressed at 98MPa and sintered at various temperatures for 86.4-1036.8ks, and the relation between the sintering behavior and superconducting properties was investigated. The abrupt increment of sintered density ratio was observed by the sintering at 1198K after gradual increment with rising sintering temperature up to 1173K, and it remained constant in the higher sintering temperature range than 1198K. Though the sintered density ratio was about 72% even after sintering at 1173K for 1036.8ks, it exceeds 90% in the case of sintering at 1223K for 1036.8ks. The marked degradation of superconducting properties was recognized in the specimen sintered at 1223K for 759.6ks, where the lamella structure along the grain boundary due to the liquid phase formed during sintering was observed.