In-situ deposition of YBCO/CeO/sub 2/ on biaxially textured Ni alloy tapes by thermal coevaporation

We report on the in-situ preparation and characterization of coated conductors consisting of a approximately=400 nm thick YBCO superconducting film grown by thermal co-evaporation on a approximately=200 nm thick CeO/sub 2/ 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 CeO/sub 2/ 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 degrees C. The backfilling of the chamber with oxygen during the cooling-down of the substrates after deposition of the CeO/sub 2/ layer greatly improves the degree of crystallization of the buffer layer. YBCO films show good superconducting properties with critical temperatures T/sub c/ of the order of 87 K. Work is in progress to scale up the process for long tapes.