High current capacity textured thick films of YBCO on YSZ obtained by melt processing

Abstract

By processing thick films of YBCO on stabilized zirconia at temperatures in excess of the peritectic value critical current densities in excess of 10 3 A cm −2 have been obtained at 77 K in film thicknesses of ≈ 40 μm. The microstructures of these films include extensive, crystalline sheets which appear to have been produced from a liquid phase system. These sheets are strongly textured with the c-axes perpendicular to the substrate. With increasing processing temperature, severe microcracking appears, resulting in a major limitation on the current carrying capacity. Variable thickness microbridges cut into the films exhibit many features characteristic of Josephson junctions. The addition of silver to these thick films during processing greatly improves their surface morphology, increases the degree of texture obtained and results in critical current densities in excess of 1300 A cm −2 at 77 K.