Preparation and Superconducting Properties of [Ln, Ce, (Ba1-xSrx)]8Cu6Oz (Ln=Nd, Sm and Eu)

Abstract
Superconductors of a new type, which belong to the [Ln1/2Ce1/6(Ba1-x Sr x )1/3]8Cu6O z system, were prepared. The crystallographic structures of all the samples were tetragonal. The samples exhibited superconducting transitions in both electrical resistivity and ac magnetic susceptibility. The Meissner signal at 20 K of [Nd1/2Ce1/6(Ba0.625Sr0.375)1/3]8Cu6O18.45 (T c on=40 K) was about 13% of the perfect diamagnet. Not only the oxygen content, z, but also the substitution of Sr for Ba, x, as well as the ionic radius of the lanthanide element, Ln, in [Ln1/2Ce1/6(Ba1-x Sr x )1/3]8Cu6O z were found to affect the superconducting properties.