In-Situ Deposition of YBCO/CeO2 on Biaxially Textured Ni Alloy Tapes by Thermal Coevaporation

We report on the in-situ preparation and characterization of coated conductors consisting of a ¡Ö 400nm thick YBCO superconducting film grown by thermal co-evaporation on a ¡Ö 200nm thick CeO2 buffer layer grown by e-beam evaporation on biaxially textured Ni-Cr and Ni-V substrates. We studied the degree of texture of both YBCO and CeO2 layers as a function of substrate temperature during deposition and of oxygen partial pressure. X-ray diffraction patterns reveal that the highest degree of (100) texture of the buffer layer, necessary for the subsequent growth of the YBCO film with the desired c-axis orientation, is achieved at substrate temperatures of the order of 670-730¡ãC. The backfilling of the chamber with oxygen during the cooling-down of the substrates after deposition of the CeO2 layer greatly improves the degree of crystallization of the buffer layer. YBCO films show good superconducting properties with critical temperatures Tc of the order of 87K. Work is in progress to scale up the process for long tapes.