Crystal Structure and Characterization of the New Tl(La, Sr)2CuO5-Type Superconductor

Abstract
We have discovered a new superconductor Tl(La, Sr)2CuO5 with transition temperature of about 40 K. The crystal structure of this material was determined by Rietveld analysis of powder X-ray diffraction data. The result indicates Cu-substitution for the Tl site and/or deficiency in the Tl site, and location of La and Sr on the Sr site in the Tl-O monolayer TlSr2CuO5 compound: the compounds have general formulas Tl1-x LaSrCu1+x O5 and Tl1-x LaSrCuO5. In both systems, superconducting properties were improved by Cu-substitution for the Tl site and deficiency of the Tl site.