Superconductivity with Tc(zero) above 105 K in Tl-containing septenary oxides with Y1Ba2Cu3Oy-like structure

Abstract

A family of high-Tc superconductors with Tc(zero) above 105 K is described. The compounds are seven-element blends with the general formula Tl0.5Pb0.5Ca0.8A0.2Sr2Cu2Ox (A=Y), and rare-earth elements La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb). The results represent one of the first cases where chemical substitution has significantly raised Tc in a known compound. The septenary compounds are tetragonal in structure with almost identical lattice parameters to those of now-famous Y1Ba2Cu3Oy structure. The samples were highly reproducible, stable and remarkably homogeneous both in composition and structure. The preparative conditions were found to be much less stringent than those of other copper-based high-Tc superconductors. © 1990.