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

The formation of the YBa₂Cu₃O_7-y layer has been investigated by a diffusion process as basic research for high-T_c superconductor fabrication. The starting materials were Y₂BaCuO₅ and barium cuprate. A dense layer of YBa₂Cu₃O_7-y was formed on a Y₂BaCuO₅ 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/cm² (77 K, 0 T) were achieved in the layer. Preparation conditions and superconducting properties, particularly J_c characteristics, are investigated. The diffusion phenomena that result in the formation of the YBa₂Cu₃ O_7-y phase by this process are also discussed