A Revised Structural Model for the Ba-Y-Cu-O Superconductor

Abstract
A possible structure with a space group Pmmm is proposed for a superconducting oxide, Ba2YCu2O7, on the basis of Rietveld analysis of X-ray powder diffraction data. It has a metal-ordered, layered structure in which an oxygen atom at a 1c site is deficient completely, and 1b and 1e sites are partially occupied. Each layer consists of those pyramids and octahedra of oxygen atoms which are linked with each other by sharing corners.