Effects of some additional elements on the reaction diffusion in high-T_coxide composites

Abstract

T h e reaction diffusion between a substrate of high melting point and a coating layer of low melting point produces a thick superconducting layer with a uniform composition.The addition of Ag to the coating layer enhances the diffusion in both Y-Ba-Cu-0 and BiSr-Ca-Cu-0 systems.The Ag is pushed out from the superconducting layer to the surface of t h e specimen, forming a laminated structure composed of a superconducting layer and an Ag layer.This movement of Ag improves t h e grain orientation in the superconducting layer.Meanwhile, the substitution of Li for Cu in the coating layer of the 6iSr-Ca-Cu-O system significantly promotes the diffusion, and a T, of 85 K is obtained after t h e reaction at 780Tfor30 min.