Crystallization and in-plane alignment behavior of YBa2Cu3O7−y films on MgO(001) prepared by the dipping-pyrolysis process

The effects of annealing temperature and oxygen partial pressure [p(O2)] were investigated on the crystallization and orientation of YBa2Cu3O7−y (YBCO) films on MgO(001) prepared by the dipping-pyrolysis process. The c-axis oriented films without in-plane alignment were prepared by annealing in the YBCO-unstable region, i.e., at low initial p(O2) of 10−4−10−3 atm and 950 °C followed by O2 treatment, through intermediate Y2BaCuO5 and liquid phase. In-plane aligned c- or c/a-axis films were prepared by similar heat treatment with an initial p(02) of 10−4 atm and 900–925 °C through a mixture of BaCu2O2 and YBa3Cu2O6+x. In contrast, nonoriented YBCO films were obtained by annealing at higher initial p(O2)'s and lower temperatures, i.e., by direct reaction among Y2O3, BaCO3, and CuO.