THE RELATION BETWEEN SUPERCONDUCTIVITY AND CRYSTAL STRUCTURE OF Tl-Ba-Ca-Cu-O SYSTEM

Abstract

It was found that the same compositional samples showed different superconducting behavior and diffraction patterns due to different heat treatment. It is interesting to note that there exist at least three superconducting phases in Tl-Ba-Ca-Cu-O system. All of them belong to the space group [Formula: see text]. They have the same lattice constant a but different lattice constant c. The transition temperature Tc is closely related with the lattice constant c. The superconducting phase with bigger lattice constant c has higher Tc. A structure model, which can generalize all of the structure of high Tc superconductors, is proposed.