粉末および焼結体YBa_2Cu_3O_<7-x>の高温における相安定性と微細構造変化

概要

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The phase stability and the change of the microstructure of the high-T_c. superconducting oxide, YBa_2Cu_3O_<7-x>, at high temperatures in the air were investigated using two samples, a powder and a sintered material. On the basis of DTA analysis, which showed endothermic reactions at 977°and 1050℃ in the air, the two samples were annealed at 950°, 990℃ for the specified periods and, quenched into liquid nitrogen. The changes of the phase and the microstructure were determined by X- ray powder analysis and the SEM observation. It is confirmed that the tetragonal phase YBa_2Cu_3O_<7-x> can exist as a single phase at 950℃, and the phase and the microstructure change at 990℃. The YBa_2Cu_3O_<7-x> phase cannot exist, and decomposes to a crystalline phase of Y_2BaCuO_5 and a liquid phase of ・BaO nCuO at 1070℃. On the basis of these results, the phase transformation and the phase diagram were discussed.
社団法人日本セラミックス協会の論文
1988-04-01