Epitaxial growth of CSD modified lanthanum zirconium oxide buffer layer for coated conductors

Abstract

Texture and morphology evolution of modified Lanthanum Zirconium oxide (LaZr1.1Oy) films grown on biaxially textured Ni5%W tapes by chemical solution deposition (CSD) method at different heat-treatment conditions has been investigated. Results show that both the growth orientation and surface morphology of films are dependent on the heating rate and annealing temperature during heat-treatment process. Compared with the annealing temperature, heating rate shows a greater influence on the orientation growth of CSD-LaZr1.1Oy film. Slow heating rate is beneficial to a single (00l) orientation growth of LaZr1.1Oy grains on textured Ni-5at.%W (Ni5W) substrate. However, the surface morphology analysis reveals a minor effect of heating rate on the grain size and surface roughness of LaZr1.1Oy film. We consider that a slow heating rate would lead to the homogeneity nucleation of LaZr1.1Oy grains and eventually forming the great textured film due to the narrow temperature interval of the complete decomposition for LaZr1.1Oy precursor gel. In any case, high-quality LaZr1.1Oy film has been achieved at annealing temperature of 900 °C with heating rate of 2 °C/min. Moreover, we have grown epitaxial CeO2 film on the textured Ni5W substrate covered by LaZr1.1Oy film using CSD approach. CeO2 precursor solution was spin-coated on short sample of Ni5W/LZO and then heat-treated at 1000 °C for 30 min in Ar-4%H2. Detailed XRD and AFM studies indicate that CeO2 film has sharp bi-axial texture and smooth surface. These results demonstrate that a low-cost CSD LaZr1.1Oy film can act as a planarization template for the further production high Jc YBCO-superconducting film.