Influence of the substrate microstructure on the superconducting properties of YBCO coated conductors

The microstructure of Ni-5at%W (Ni-W) and Ni-11at%V (Ni-V) biaxially textured substrates has been investigated using X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). The correlation between the substrate microstructure and superconducting transport properties of YBa₂Cu₃O_7-y (YBCO) film grown on it has been studied on the YBCO/CeO₂/Ni-W and YBCO/CeO₂/NiO/Ni-V architectures. Our study has ascertained that the in-plane texture of the substrates is one of the most important factors, limiting the critical current density. The Ni-V substrate has a lower percolation area due to the larger number of twinned grains and a broader in-plane angular distribution and, as a consequence, the YBa₂Cu₃O_7-y (YBCO) film grown on it has a critical current density of 0.6 × 10⁶ A/cm², depressed by factor 2 with respect to YBCO grown on the Ni-W substrate. For the Ni-V substrate, another limiting factor is its low oxidation resistance. In contrast to Ni-V, the Ni-W substrate has a larger percolation area, mainly due to the absence of twinned grains, and a high oxidation resistance.