Development of YBCO film approached by TFA-MOD method using the Y2Ba1Cu1Ox and Ba3Cu5O8 powders

The YBCO films were fabricated by TEA-MOD method in route of "211 process" and evaluated the phase formation, texture evolution, and critical current and critical temperature as a function of the humidity firing process. In the fabrication process, Y₂Ba₁Cu₁Ox and Ba₃Cu₅O₈ powders, instead of Y-, Ba- and Cu-based acetates, were used as precursors. In order to evaluate the effect of humidity during the firing process, the films calcined at 430 °C were fired at 775 °C in dry Ar(0%), 4.2%, 8.0%, 12.1%, and 20.0% humidified Ar gas mixed with 1000 ppm oxygen. We observed that the amount of BaF₂ phase was effectively reduced and that a sharp and strong biaxial texture formed under a humidified atmosphere, leading to increased critical properties. The film became denser and the degree of texture and phase purity varied as the humidity increased. For the film fired in 0% humidity, the measured value of T_c(onset) was found to be 82.5 K, but the T_c(zero) could not be measured. When the humidity was increased to 4.2%, the corresponding T_c(onset) and T_c(zero) were increased to 91.5 K and 88.6 K, respectively. For the films in the humidity range of 12.1-20.0%, the critical current density was found to be 1.54 MA/cm².