Effect of samarium and lanthanum substitution on the stability of superconductive properties of YBa2Cu3O x

The effect of annealing conditions and solute substitution of samarium and lanthanum on the oxygen deficiency and superconductive properties of YBa2Cu3Ox-based compounds has been examined. The oxygen deficiency which occurs in samples cooled in air from temperatures above about 400 °C gives poor superconductivity. Although the oxygen content did not change in the samples cooled in a furnace, a degradation of superconductivity, which may be responsible for the formation of lattice imperfections including incipient twin-like bands, was noticed. A partial replacement of yttrium by samarium is found to be effective for stabilizing the superconductivity.