Large area YBCO films on polycrystalline substrates with very high critical current densities

We deposited large-area YBCO films by reactive thermal co-evaporation on biaxially textured, Y/sub 2/O/sub 3/ stabilized ZrO/sub 2/ (YSZ) buffer layers fabricated by an IBAD technique (ion beam assisted deposition). Polycrystalline, partially stabilized ZrO/sub 2/ (PSZ) with a size of 10/spl times/10 cm was used as a substrate. Homogeneous, biaxially aligned IBAD buffer layers were prepared by using large ion guns and substrate rotation during the IBAD process. YBCO films with thicknesses of up to 1400 nm were deposited. The biaxial alignment of the buffer layer and of the YBCO film was characterized by X-ray diffraction. The FWHM of YSZ [111] /spl phi/-scans varied laterally within a range of 15/spl deg/ to 20/spl deg/. The FWHM of the YBCO [103] was always several degrees better with value of only 7/spl deg/ to 9/spl deg/. The YSZ thickness dependence of this improvement was analyzed. We achieved a mean critical current density of 1.9 MA/cm/sup 2/ and a maximum critical current density of 2.1 MA/cm/sup 2/ on a substrate area of 10/spl times/10 cm.