Preparation of the High-T_c Superconductor Pb₂Sr₂Y_0.5Ca_0.5Cu₃O_8+δ with Zero Resistance at 75 K

Abstract

Good quality samples of the high- T c superconductor Pb 2 Sr 2 Y 0.5 Ca 0.5 Cu 3 O 8+δ have been prepared by solid-state reaction under low oxygen pressure and adequate post-annealing in flowing nitrogen gas. The best sample shows metallic temperature dependence of the resistivity above T c , an onset of the superconducting transition at 83 K and zero resistance at 75 K. The adequate post-annealing, which is considered to decrease crystalline disorder, is effective in attaining good superconducting quality.