High temperature superconductivity in Sm-Ba-Cu, Sm-Ca-Cu and Y-Ba-Cu oxidized alloys

Superconducting compounds were prepared by oxidizing induction melted ternary mixtures of rare earth elements (RE), Cu, and D elements (Ca or Ba). Alloy compositions were 95 wt.% Cu + 5 wt.% (RE + D) having the atomic ratio of RE:D = 1:2. Sections were cut from the solids, polished, and then annealed. The Sm--Ca--Cu alloy was annealed at 600K/30 min in air and 600K/30 min in oxygen, and it showed a superconducting transition temperature, T sub c , of 39K. The Sm--Ba--Cu alloy was oxidized, as was the Sm--Ca--Cu alloy, and it showed a T sub c of 53K; when annealed further at 600K 30 min in O, T sub c was 66K. The Y--Ba--Cu alloy was annealed at 600K/1 h in air and 600K/30 min in O, and it had T sub c s of 84.5, 85.5, and 92.0K, depending on the test current near 10 exp --4 A. 10 ref.--J.J.P.