Preparation and characterization of Y/sub 2/O/sub 3/ buffer layers and YBCO films on textured Ni tape

The direct deposition of Y/sub 2/O/sub 3/ buffer layers on cube-textured nickel tape was successfully performed by electron beam deposition using Y metal which oxidized during deposition. The Y/sub 2/O/sub 3/ layer exhibited excellent out-of-plane alignment of FWHM of 2.3/spl sim/4/spl deg/ and good in-plane alignment with /spl sim/11/spl deg/ FWHM. Surface morphology, crystal orientation and grain size proved to be quite sensitive to the deposition pressure. The surface roughness and the grain size increased with increasing deposition pressure, and the crystal orientation changed from [111]Y/sub 2/O/sub 3/ to [100]Y/sub 2/O/sub 3/. Subsequently, YBCO superconducting films were deposited on [100]Y/sub 2/O/sub 3/ buffer layers by co-evaporation deposition and pulsed-laser deposition (PLD). Though a good in-plane alignment, as measured by X-ray /spl phi/-scan, was achieved in the YBCO films, their superconducting characteristics were not so good. The T/sub c/ onset was about 84 K for the [001]YBCO by PLD. The crystal alignment and the microstructure of YBCO superconducting films deposited by the two deposition techniques on cube-textured Ni tapes with Y/sub 2/O/sub 3/ buffer layers are compared.