ホットプレスを用いたBi-SrCa-Cu-O系セラミックスの超伝導特性

概要

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The superconducting properties of the Bi-Sr- Ca- Cu- O ceramics has been studied in terms of the microstructure. The powders were uniaxially hot pressed at 5 t/cm^2, 500℃ for 5 min. Then the compacts were heated and sintered again at 870℃ in air for 10 and 100 h, followed by furnace cooling. Resistivity of the specimens was measured by standered four-probe method. Zero resistivity was observed at 80.0 K when the compact was heated at 870℃ for 10 h, while after heated for 100 h the off-set was at high as 105.5 K. The critical current density at 77 K was very low as 168.4 mA/ cm^2. The specimens simply heated and sintered at 870℃ for 10 ard 100 h after cold pressing at 5 t/cm^2 (without hot pressing) showed very low off-set temperatures. It was found, however, that the prolonged heating at 870℃ with or without hot pressing increased the formation of the high T. phase in the Bi-Sr- Ca- Cu- O ceramics. The hot pressing prior to the heating at 870℃ increased the bulk density and the grain sizes of the specimens. The improvement of the sintering behavior may assist the formation of superconducting contacts among the grains of the high T_cphase in the Bi-Sr- Ca- Cu- O ceramics.
社団法人日本セラミックス協会の論文
1989-09-01