Fabrication of Y_2O_3 buffer layer on polished Ni substrates for YBCO superconducting tape

摘要

Highly cube textured Ni tapes are produced by heavy cold rolling and recrystallization annealing. The textured nickel tapes have been proven to be suitable substrates for YBCO superconducting tape. Nevertheless, rolling damage and grain boundary grooves on Ni influence the epitaxial growth of highly textured buffer and YBCO layers. The polishing of the Ni substrate surface may play a crucial role in making it beneficial to epitaxial film deposition. In our work, several polishing methods were adopted on Ni to reduce the depth of rolling damage and grain boundary grooves. On the polished Ni substrates, textured Y_2O_3 buffer layers were deposited using RF sputtering. XRD results show that in-plane texture of Y_2O_3 films will minish with the decreasing of the Ni substrate surface roughness. AFM results show that average grain size of the Y_2O_3 film is biggest and surface is coarse in film on flatter Ni surface.