Crystalline Phases in Superconductor Ba-Y-Cu-O with High Tc Prepared by Melting Method

Abstract

A superconducting Ba-Y-Cu-O oxide with high T _c was prepared by a melt quenching method, and the effect of melt quenching conditions on the value of T _c and crystalline phases in quenched and annealed samples was examined. It was found that the values of T _c,zero for annealed samples were 88 or 89 K, irrespective of the first melt quenching conditions. The crystalline phases in quenched samples were a mixture of Y₂O₃ and BaCuO₂, and the main crystalline phase in annealed samples was orthorhombic Ba₂YCu₃O_7-δ Superconducting Ba₂YCu₃O_7-δ oxides were formed very easily by annealing the melt quenched samples.