Effect of the firing process on the critical current density of YBa2Cu3O7-x films derived from the sol-gel method

The firing process plays a crucial role on the microstructures of sol-derived YBa2Cu3O7-x (YBCO) films; thus, it affects the critical current density, Jc, of the films. In this paper, the effect of the oxygen partial pressure-temperature (PO2-T) combination during the firing process on the microstructure and Jc of an YBCO film derived from a low-fluorine sol-gel method was investigated. The results indicate that the optimal PO2-T combination for a high-Jc YBCO film is different from that derived from an in-situ deposition reported previously. When the optimal PO2-T combination is adopted, the resulting YBCO films exhibit good biaxial texture characteristics and dense surfaces over the entire firing temperature range of 700-775 °C. In addition, the YBCO films exhibit a Jc of above 2 MA/cm2, even though they are fired at 700 °C. Moreover, Jc is near 10 MA/cm2 for the YBCO film fired at 775 °C.