Preparation of large-size Y123 films on CeO2-buffered sapphire substrates by MOD using a low-cost vacuum technique

Abstract

High-Jc YBa2Cu3O7 (Y123) films with good homogeneity have been obtained on CeO2-buffered sapphire substrates by metal organic deposition (MOD) using a low-cost vacuum technique; only nitrogen gas and air instead of a high-purity gas mixture of argon and oxygen were supplied in the high-temperature heat treatment. A 2cm×12cm rectangular Y123 film was prepared in a large-size tube furnace with uniform temperature zone. The total pressure and oxygen partial pressure in the furnace were controlled by the flow rates of nitrogen and air and by evacuation speed of a rotary pump. The apparent inductive-Jc values, except those at a few positions near the film edges, were within 3.0±0.3MA/cm2, i.e., the fluctuation of Jc was within ±10% of the average. Comparison of the spatial distributions of Ic, film thickness and XRD intensity of Y123 suggests that the crystallinity of Y123 and Jc values at local points are uniform over the film and the thickness distribution affects the local Ic values, or apparent Jc distribution.