CuO formation control as a function of mixed ratio of Cu-free powders in the synthesis of YBCO superconductors on Cu substrates

Abstract

YBa2Cu3Ox (Y123) superconducting films were fabricated on Cu substrates using a simple screen-printing method, from Cu-free powders (Y2O3 and BaCO3). In the process, CuO, which causes superconducting properties of Y123 films to deteriorate, was formed on the film surface. By varying the atomic ratio of Y to Ba (Y:Ba = 1:1 similar to 1:4), the ratio needed to prevent CuO formation was found for the film surface that had been heat-treated at 980 degrees C for 17 s. The film, with the ratio of Y to Ba (Y:Ba = 1:1), is reheat-treated at 930 degrees C for 9 min 30 s to form a superconducting Y123 phase. It was possible to prevent CuO formation by controlling the ratio of Cu-free powders in the mixture and to fabricate YBCO superconductors on Cu substrates using a two-step heat-treatment.