Microstructure and Interface Phase Formation in YBa2Cu3O7−δ Prepared by an MOD Process

Understanding the evolution of microstructure in YBCO (YBa₂Cu₃O_7-zeta) is critical to optimizing the process for production of high quality superconducting wire for commercial applications. Therefore, microstructure and interfaces have been investigated in fully reacted YBa₂Cu₃O_7-zeta, prepared by the metalorganic deposition (MOD) process, and deposited on CeO₂/YSZ/Y₂O₃/NiW. YBCO nucleates on CeO₂ with a specific orientation relationship where [011] CeO₂ || [100] YBCO and (200) CeO₂ || (002) YBCO, and with the [001] YBCO axis parallel to the film growth direction. A 25-50 nm thick reaction layer of BaCeO₃ was observed at the YBCO : CeO₂ interface. Formation of this layer releases a considerable amount of Cu and Y into the YBCO matrix. Details of the interfacial phase formation in the MOD-processed YBCO films are presented in this paper.