酸化物超伝導セラミックスの微構造と臨界特性

概要

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The oxide superconducting ceramic Ba2YCu3O7 is sensitive to environmental degradation. The significant deterioration seen for specimens annealed in air may be attributed to the combined effect of H2O and CO2. It has been found that this degradation could be lessened by the densification of bulk superconductor prepared from co-precipitated oxalate powder. We also investigated the effect of processing and microstructual control on the critical current density of Ba2YCu3O7. Materials sintered from co-precipitated powders showed sintered densities up to 98.5% of theoretical value and were composed of a large number of plate-like grains ( 20-100μm long, 5-10μm thick ).The critical current density of highly dense samples at 77K under zero magnetic field remained at 350 Acm-2 probably due to the presence of micro-cracks. Jc of the lower density sample ( 90% ) was larger than that of the high density sample. This might be due to a decrease in a large number of micro-cracks.
社団法人粉体粉末冶金協会の論文