High Pressure Syntheses of Superconductors in Y System and Their Related Materials

Abstract

High pressure synthesis was performed on 123 and 124 phases in Y-Ba-Cu-O system under a pressure of 3GPa at 950°C. Lattice parameters and superconducting properties changed with an annealing duration under pressure in 123 phase with oxygen content X=7. The 123 product obtained from raw materials with X=8.5 had a tetragonal lattice with a=c/3=3.87A. Its real oxygen content could be estimated to be 7.3 from the lattice parameter, Raman spectroscopy, and also Rietveld analysis. The product seemed to be semiconductor containing a small amount of superconductor. 124 phase was obtained by a reaction at 950°C with its successive annealing at 700°C under 3GPa adjusting oxygen content of raw material to the exact composition of the product. © 1991, Japan Society of Powder and Powder Metallurgy. All rights reserved.