Superconductivity in Ba-Ln(lanthanoid)-Cu-O Compounds

Superconductivity observed in the temperature dependence of the resistivity for Ba-Ln(lanthanoid)-Cu-O compounds with a nominal composition of Ba 0.6 Ln 0.4 CuO 3- x is reported. The compounds are classified into two groups according to the nature of the superconducting transitions and the structures. Those ones with a single perovskite-like phase, where Ln=Nd, Sm, Eu and Gd, showed smeared transitions with relatively low critical temperatures. The other compounds with mixed phases, where Ln=Dy, Ho, Er, Tm, Yb and Lu, have critical temperatures above 90 K with narrow transition widths.