Growth of biaxially oriented conductive LaNiO₃ buffer layers on textured Ni tapes for high-T_c-coated conductors

Electrically conductive LaNiO₃ buffer layers have been grown on textured nickel tapes by sputter deposition in a reducing atmosphere. These conductive buffered Ni tapes can be employed as long flexible substrates for biaxially aligned high-temperature superconductors, and can electrically stabilize the superconductor during transient loss of superconductivity. Deposition temperatures of about 400 °C result in epitaxial growth of LaNiO₃ films, while higher deposition temperatures may cause the formation of La₂NiO₄ films. X-ray θ-2θ, θ, and φ scans reveal that the LaNiO₃ films have good out-of-plane and in-plane orientations of 5° and 9-10 °C, respectively. Subsequent oxygen anneals at 750 °C and 850 °C change neither the biaxial orientations of the film nor cause any cracks or other surface defects. The resistivity of the LaNiO₃ films can be further reduced by increasing the annealing temperature and oxygen pressure during post-annealing. Highly textured YBa₂Cu₃O₇ (YBCO) films were grown on the LaNiO₃-buffered Ni by pulsed laser deposition (PLD).