Phase Compatibility and Superconductivity of Y-Ba-Cu-O Compounds

Abstract

Superconducting properties of Y-Ba-Cu-O compounds were investigated in relation to precipitation of second phases. Contour lines of J c , T c and diamagnetic signal intensities were presented in the YO 1.5 -BaO-CuO system. These superconducting properties decreased steeply with BaCuO 2 precipitation, and the maximum J c was obtained in the yttrium-rich composition of Y 1.2 Ba 2 Cu 3 O 7- y . It is considered, therefore, that the BaCuO 2 precipitating around the YBa 2 Cu 3 O 7- y grains interrupt the superconducting current pass at the grain boundary. Yttrium-rich composition, which inhibits BaCuO 2 precipitation, is effective for the preparation of the high- J c sample.