Superconductivity in ABa₂Cu₃O_7-xcompounds, where A=(R₁)_x(R₂)_1-xand R₁, R₂=Y, Sm, Eu, Gd, Tb, Dy, Yb, Zr and Nb

Abstract

The electrical resistance has been measured for a series of compounds ABa2Cu3O7-x where A=(R1)x(R2)1-x and R1, R2=Y, Sm, Eu, Gd, Tb, Dy, Yb, Zr and Nb. All the compounds show superconductivity at about 90 K. A magnetisation measurement has been made at 77 K as a function of magnetic field.