A superconducting oxide with a stoichiometry La/sub 3/CaBa/sub 3/Cu/sub 7/O/sub 15.5+x/, in which x=0.75, was prepared. It had a tetragonal triple-perovskite structure with lattice parameters a=3.879.ANG. and c=11.637.ANG.. According to resistivity measurements, a sharp superconducting transition,.DELTA.T/sub c/(10-90%)=1.5K, and T/sub c(zero)/=80K were observed. When it was measured at a small magnetic field(10-20 gauss) with field cooling, the sintered pellet showed a positive magnetic susceptibility, but the powdered sample exhibited the diamagnetism of a typical superconductor. However, no peculiar shielding effect was found in both the sintered and powdered samples.
Journal of the Chinese Chemical Society=中國化學會會誌 39(1), pp.67-69