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

Abstract

ABSTRACTThe YBCO films were fabricated by TFA-MOD method in route of ¡°211 process¡± and evaluated the phase formation, texture evolution, and critical properties 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¡É were fired at 775¡É 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 Tc(onset) was found to be 82.5 K, but the Tc(zero) could not be measured. When the humidity was increased to 4.2%, the corresponding Tc(onset) and Tc(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 was found to be 30 A/cm-width (the corresponding critical current density is 1.54 MA/cm2).