New processing technique of TFA-MOD YBCO coated conductors using the '211' process

We fabricated the YBCO films on single crystal LaAlO3 substrates via a metal organic deposition (MOD) process. In the process, Y2Ba1Cu1Ox and Ba3Cu5O8 powders were dissolved in trifluoroacetic acid (TFA) followed by calcining and firing heat treatments. To evaluate the effects of the firing temperature on YBCO phase formation and critical properties, the films were fired at 750 degrees C, 775 degrees C and 800 degrees C after calcining at 430 degrees C. Microstructure observation indicated that a crack-free surface formed and a strong biaxial texture was developed. The FWHM of out-of-plane texture was measured to be in the range of 4.3 - 7.0 degree for all the films. When the YBCO film was fired at 775 degrees C, it had the highest critical properties: 88.5 K of critical temperature and 16 A/cm-width of critical current (1MA/cm2 as critical current density). On the other hand, those properties were degraded as firing at 750 degrees C and 800 degrees C. It is considered that the improved critical values are partly owing to dense and homogeneous microstructure, strong texture, and high oxygen content.