Pulsed laser deposition of high critical current density YBa₂Cu₃O7 x/CeO₂/Ni W architecture for coated conductors applications

Epitaxial YBa 2 Cu 3 O 7− x (YBCO) films with critical current densities exceeding 1 MA cm −2 (at 77 K in self magnetic field) were epitaxially grown on biaxially textured Ni 5 at% W (Ni–W) substrate using only a CeO 2 buffer layer. Both YBCO and CeO 2 films were deposited in situ by pulsed laser ablation. The oxidation behaviour of the Ni–W substrate enables the epitaxial growth of a CeO 2 oxide buffer layer without using the forming gas (Ar 4%H 2 ). SEM investigations of YBCO and CeO 2 films reveal a dense microstructure without cracks or porosity. X-ray pole figures show a cube-on-cube epitaxy with a [100]YBCO//[110]CeO 2 //[100]Ni–W epitaxial relationship. The YBCO superconducting film has a good out-of-plane and in-plane texture with a full-width-half-maximum of 5.8° and 6.6°, respectively. No severe degradation of J C with film thickness, up to 1 μm thick films, was observed. The use of a single buffer layer on Ni–W substrates represents an important simplification in the scaling-up for long tape fabrication.