Effect of tungsten substitution in the YBa2Cu3O7−x system

A series of YBa₂Cu_3−x oxides was synthesized. The results show a cubic system with a simple perovskite structure for x < 0.2 and a face-centered doubled perovskite cell for x > 0.2. There was no indication of the existence of the superconducting 1-2-3 phase for x > 0.2. Solid solution of tungsten was exhibited over the composition region 0.2 < x as well as in the simple perovskite composition range. Analyses of a sample of nominal composition YBa₂Cu₂W oxide indicates a non-superconducting perovskite with .