Preparation and Superconducting Properties of the Ba1-xYxCuO3-y Compounds

The Ba1-x Y x CuO3-y compounds with x ranging from 0.1 to 0.6 were prepared under various sintering conditions. The Ba0.66Y0.34CuO3-y compound, prepared by sintering at 950°C for 24 hours after presintering at 950°C for 1 hour, showed superconductivity with T c onset=90 K, T c midpoint = 88 K and T c end = 85 K. The compound is a single phase of oxygen-defect perovskite. Magnetization curves were measured at 77 K and the values of H c1 were estimated.