RHENIUM AND RHENIUM OXIDE AS BUFFER LAYERS FOR HIGH T-C THIN-FILMS ONMETALLIC SUBSTRATES

High T-c superconductor films on metal wires for high power applicatio ns must show longterm stability. Suitable buffer layers are required t o prevent interaction between the superconductor thin films and the su bstrate, and to improve the long-term stability. A high melting-point metal, rhenium, and its oxide, were sputter deposited on the metallic substrate, Hastelloy. The study showed that rhenium thin films were re sistant to out-diffusion from the Hastelloy substrates. However, it wa s found that they are easily oxidized at high temperature and they are , therefore, not suitable to oxygen rich high T-c superconductors like YBCO. They might work with other types of high T-c superconductors wh ich have a lesser oxygen dependence.