CRYSTALLIZATION AND INPLANE 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(O-2)] 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(O-2) of 10(-4)-10(-3) atm and 950 degrees C followed by O-2 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(O-2) of 10(-4) atm and 900-925 degrees C through a mixture of BaCu2O2 and YBa3Cu2O6+x. In contrast, nonoriented YBCO films were obtained by annealing at higher initial p(O-2)'s and lower temperatures, i.e., by direct reaction among Y2O3, BaCO3, and CuO.