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 mu m to 2.14 pm 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 mu m to 1.17 mu m. On the other hand, the corresponding J(c) remained almost constant in the range of 0.76-0.90 MA/cm(2). With further increases in thickness, these values decreased drastically, which was attributed to the degraded microstructure, i.e., the formation of BaF2 and alpha-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 mu m. (C) 2007 Elsevier B.V. All rights reserved.