PHASE EQUILIBRIA AND CRYSTAL CHEMISTRY IN THE SYSTEM Ba-Y-Cu-O*

Abstract

Preliminary phase equilibria diagrams are constructed for the binary systems BaO-{1/2}Y{sub 2}O{sub 3}, BaO-CuO{sub x}, {1/2}Y{sub 2}O{sub 3}-CuO{sub x} and the ternary system BaO-{1/2}Y{sub 2}O{sub 3}-CuO{sub x}. Some melting data are used to outline an approximate primary field for the phase responsible for high temperature superconductivity in this system, Ba{sub 2}YCu{sub 3}O{sub 7-x}. A discussion is given of the crystal chemistry of the phase(s) near the composition Ba{sub 3}YCu{sub 2}O{sub x}.