Preparation of YBa₂Cu₃O_7−y films on SrTiO₃ and MgO by the dipping-pyrolysis process under low-p(O₂) heat treatment

Superconducting YBa₂Cu₃O_7−y (YBCO) films having a thickness of 1 μm were prepared on SrTiO₃(100) and MgO(100) by the dipping-pyrolysis process using a low-p(O₂) annealing method. Heat-treatment conditions were varied along the upper limit of the stability region of the YBCO phase. Films on SrTiO₃(100) exhibited strong c-axis orientation with sharp rocking curves (FWHM = 0.8°). The highest T_c,zero of 87 K was obtained for the film heat-treated at 750 °C. On the other hand, films on MgO(100) showed broader rocking curves and their T_c's remained lower. Moreover, Ag addition was found to enhance the T_c values (T_c,zero = 91 K) of films on SrTiO₃ heat-treated at 750 °C.