High J/sub C/ YBCO films on biaxially textured Ni with oxide buffer layers deposited using evaporation and sputtering techniques

Epitaxial buffer layers of CeO/sub 2/ and Yttria-stabilized ZrO/sub 2/ (YSZ) have been deposited on biaxially textured nickel substrates using thermal reactive evaporation, electron beam evaporation and rf sputtering. The buffer layers were characterized by XRD, SEM and optical microscopy. YBCO films were deposited by high-pressure dc sputtering on CeO/sub 2//YSZ/CeO/sub 2/ buffered substrates and the resulting superconducting properties were measured inductively. On exclusively evaporated buffer architectures critical current densities of 0.6 MA/cm/sup 2/ (77 K, H = 0 T) were measured. The buffers showed some cracks after YBCO deposition, which we considered to be responsible for the relatively low J/sub c/. Buffer architectures with evaporated CeO/sub 2/ followed by rf sputtering of YSZ and CeO/sub 2/ in oxygen atmosphere remained completely crack free after YBCO deposition. Critical current densities between 1.5 and 2.3 MA/cm/sup 2/ (77 K, H = 0 T) in 460 nm thick YBCO films were obtained reproducibly. The critical temperatures T/sub c/ ranged between 88 and 92 K and the typical width (Delta)T/sub c/ of the transition was 1.5 K.