Characterization of buffer layers on Ni-based substrates for YBCO superconductors

Metal oxide buffer layers provide a continuous, smooth textured and chemically inert surface for growth of the YBCO (YBa₂Cu ₃O₇.,) film and prevent metal diffusion from the substrate into the superconductor. CeO₂, Gd₂O₃ and Eu₂O₃ buffer layers were grown on metallic Ni substrates using a sol-gel method by using metal 2,4-pentanedionate and acetate precursors. The films were annealed at 1150°C under 4%H₂-Ar gas mixture. Textured, crack free and continuous buffer layers were obtained through the sol-gel technique. Prior to the coating process, solution characterization was performed by turbidimeter, pH meter, contact angle goniometer and rheometer. Heat treatment profiles were determined by using DTA-TG and FTIR. The coated layers were characterized by means of XRD, SEMEDS, AFM and a scratch tester. As a result, textured growth of CeO₂, Eu₂O₃ and Gd₂O₃ thin films on textured Ni tapes by the sol-gel dip coating process were successfully performed.