Distribution of inductive Jc in two-dimensional large-size YBCO films prepared by fluorine-free MOD on CeO2-buffered sapphire

Distribution of J_c in the two-dimensional large-size YBa₂Cu₃O₇ (YBCO) film was investigated by an inductive method for the application to fault current limiter elements. The YBCO films were prepared by metal-organic deposition (MOD) using a fluorine-free acetylacetonate-based complex solution on R-plane sapphire with an evaporated-CeO₂ buffer layer. The average J_c values of 1-3 MA/cm² at 77 K were obtained for 1 cm × 12 cm-, 3 cm × 12 cm-, and 10 cm × 30 cm-rectangular YBCO films as well as on 2-inch-diameter films. In contrast with the TFA-MOD method via BaF₂ precursor, the fluctuation of J_c in the present films was fairly small; no significant size effects or shape effects were recognized on the fluctuation of J_c. Instead, fluctuation of J_c depended on the average J_c values; higher-J_c films tended to exhibit more uniform J_c distribution.