Preparation of MZrO3 (M=Ba,Sr) buffer layers on surface oxidized Ni/NiO templates by PLD and MOD

The preparation of cube textured NiO buffer layers on biaxially textured Ni tapes using surface oxidation epitaxy (SOE) offers a cheap and scalable route for the production of long-length YBCO coated conductors. A second buffer layer is necessary to ensure epitaxial growth of the YBCO as well as to prevent Ni contamination of the superconducting layer. Zirconate buffer layers offer a close lattice misfit to NiO as well as a high stability during the YBCO deposition. BaZrO₃ and SrZrO₃ buffers were successfully deposited on NiO using pulsed laser deposition. Additionally, BaZrO₃ films were prepared on NiO using metal-organic decomposition. All buffers show a high quality epitaxial growth with an in-plane orientation similar to the underlying NiO. The subsequent deposition of YBCO on top of these buffers resulted in epitaxial layers with a T_c above 85 K and j_c up to 1 MA/cm² on NiO if a thin intermediate SrTiO₃ layer is used. Microstructural investigations showed that the roughness and the surface topography of the buffer layers is mainly determined by the quality of the NiO layer.