New superconducting cuprate perovskites

Abstract

Ten new superconducting cuprate perovskites with ${\mathrm{T}}_{\mathrm{c}}$'s above 77 K are reported. The highest ${\mathrm{T}}_{\mathrm{c}}$ of the new group, and for any superconductor, is observed in ${\mathrm{Ba}}_{2}$${\mathrm{Eu}}_{0.9}$${\mathrm{Y}}_{0.1}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{\mathit{x}}$ which has a resistive midpoint of 94.5 K with a width of 0.7 K. Miessner effect and ac susceptibility measurements indicate bulk superconductivity in these materials. Each of these cuprates has a two-to-one ratio of divalent to trivalent ion on the A site of the perovskite-type structure.