The effect of film thickness on critical properties of YBCO film fabricated by TFA-MOD using 211-process

YBCO films were fabricated by the TFA-MOD method using the "211-process", and the effects of the film thickness on phase formation, microstructure, texture evolution, and critical properties were evaluated. Various film thicknesses ranging from 0.41 μm to 2.14 μm were obtained by repeating the dip coating and calcining processes one to five times. The critical properties varied significantly with the film thickness. The I_c increased from 35 to 105 A/cm-width with increasing the film thickness from 0.41 μm to 1.17 μm. On the other hand, the corresponding J_c remained almost constant in the range of 0.76-0.90 MA/cm². With further increases in thickness, these values decreased drastically, which was attributed to the degraded microstructure, i.e., the formation of BaF₂ and a-axis grains and degraded texture and surface morphology arising from the insufficient heat treatment time. It is believed that the optimum thickness for improving both the I_c and J_c values is approximately 1.17 μm.