Critical current density of Y-Ba-Cu oxide superconductor prepared by a diffusion process

The formation of the YBa/sub 2/Cu/sub 3/O/sub 7-y/ layer has been investigated by a diffusion process as basic research for high-T/sub c/ superconductor fabrication. The starting materials were Y/sub 2/BaCuO/sub 5/ and barium cuprate. A dense layer of YBa/sub 2/Cu/sub 3/O/sub 7-y/ was formed on a Y/sub 2/BaCuO/sub 5/ substrate, and the starting barium cuprate layer was fully converted to the superconducting oxide. X-ray diffractometry revealed that the layer consisted of an orthorhombic crystal structure. The reacted specimens showed good superconductivity. A zero-resistance temperature of 91.5 K and a critical-current density of 1900 A/cm/sup 2/ (77 K, 0 T) were achieved in the layer. Preparation conditions and superconducting properties, particularly J/sub c/ characteristics, are investigated. The diffusion phenomena that result in the formation of the YBa/sub 2/Cu/sub 3/O/sub 7-y/ phase by this process are also discussed.>