Preparation of Superconducting 1201 Phase in the (Pb_1-yCu_y)Sr_2-xLa_xCuO_z System

Abstract

An almost-single-1201-phase sample has been synthesized in the (Pb 1- y Cu y )Sr 2- x La x CuO z system. The sample showed the superconducting transition with the onset temperature of about 36.5 K and a zero resistivity temperature of about 31.5 K. These values were about 7 K higher than those reported by Adachi et al. The X-ray powder diffraction study showed that the almost-single phase was attained at the nominal composition of x =0.9 and y =0.5, and the crystal structure had a tetragonal symmetry with a =0.3769 nm and c =0.8697 nm.