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

Abstract

Epitaxial YBa2Cu3O7−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 CeO2 buffer layer. Both YBCO and CeO2 films were deposited in situ by pulsed laser ablation. The oxidation behaviour of the Ni–W substrate enables the epitaxial growth of a CeO2 oxide buffer layer without using the forming gas (Ar 4%H2). SEM investigations of YBCO and CeO2 films reveal a dense microstructure without cracks or porosity. X-ray pole figures show a cube-on-cube epitaxy with a [100]YBCO//[110]CeO2//[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 JC 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.