Preparation of YBCO films on CeO₂-buffered (001) YSZ substrates by a non-fluorine MOD method

YBa₂Cu₃O_7-δ (YBCO) films were fabricated via a fluorine-free metal organic deposition (MOD) method followed by high-temperature, low oxygen partial pressure annealing. Trimethyl acetate salts of copper, yttrium, and barium hydroxide were used as the precursors, which were dissolved in proponic acid- and amine-based solvents. After spin-coating and burnout, samples were annealed at 740°C in 180 ppm oxygen partial pressure and exposed to humid atmosphere for different times. A critical transition temperature, T_c(R=0) of 90.2 K and a transport critical current density (J_c) of 0.55 MA/cm₂ (77 K and self-field) were obtained for 0.2 μm YBCO films on CeO₂-buffered yttria-stabilized zirconia (YSZ) substrates. X-ray studies shows that the YBCO films have sharp in-plane and out-of-plane texture for all samples; however, the porosity of the YBCO film varies with the time of exposure to the humid atmosphere. A reaction between YBCO and CeO₂ during the high-temperature anneals and formation of the reaction product BaCeO₃ was confirmed by X-ray diffraction (XRD) studies. The XRD and transmission electron microscopy analysis indicated that the epitaxial relations in the film were YBCO (00l )//CeO₂ (00l)//YSZ (00l) and YBCO [100]// CeO₂ [110]//YSZ [110].