The Effects of the Humidity and Thickness on YBCO Film Prepared Using the TFA-MOD Method

This study examined the epitaxial growth of YBa₂Cu₃O_7-x (YBCO) films on (00l) LaAlO₃ substrates prepared by metal organic deposition (MOD) using a trifluoroacetate (TFA) solution. The effects of humidity (0-20% of P_H2O) and film thickness (0.4-2.1 mum) on the phase formation, texture, and microstructures of the YBCO films were examined by X-ray diffraction, pole-figure, and scanning electron microscopy (SEM). The microstructure and resultant critical properties varied remarkably with humidity. With increasing humidity, the amount of the second phase (BaF₂) decreased, the degree of texture was enhanced, and consequently the critical current (I_C) and temperature (T_C ) were improved. In the case of multi-coated films, the I_C value increased from 35 to 152 A/cm-width with an increasing number of coatings from one to three, while the corresponding critical current density (J_C) was in the range of 0.9-1.5 MA/cm² . Both the I_C and J_C decreased when an additional coating was applied due to microstructural degradation.