(Received March 14, 1987; accepted for publication March 23, 1987)
Crystal structures of a high-Tc oxide superconductor Ba0.7Y0.3Cu1Ox have been identified using X-ray diffractometry and electron probe microanalysis. All the major diffraction peaks can be indexed in terms of the cubic and tetragonal phases. The lattice constant ac is 3.884 Å for the cubic phase and the lattice constants at and ct are 3.856 Å and 11.64 Å, respectively for the tetragonal phase. The identified phases have been confirmed on the scanning backscattered electron images of the sample and their chemical compositions have also been determined.