Effect of air humidity on the microstructure and properties of large-area YBa2Cu3O7-x films by TFA-MOD process

Large-area YBa2Cu3O7-x (YBCO) films had been successfully fabricated on LaAlO3 (LAO) substrate by metalorganic deposition using trifluoroacetates (TFA-MOD) and the effect of air humidity on the structure and properties of YBCO films was systematically investigated. The precursor coating process was performed in the air humidity range of 70-40%. According to the X-ray diffraction (XRD) and scanning electron microscopy (SEM) images, the films prepared at high air humidity showed poor electrical performance due to large pores and impurity phases. In contrast, dense, homogeneous and epitaxially grown YBCO films prepared at low air humidity with the critical current densities of 3.8-5.0 MA cm-2 at 77 K had been obtained.