Dependence of microstructures on growth rate in YBCO films by TFA-MOD method

YBa2Cu3Oy (YBCO) films grown by starting solutions with Ba-poor (Y:Ba:Cu = 1:1.5:3, Ba/Y = 1.5) have been reported to perform higher Jc than that for YBCO films with stoichiometric one due to smaller and less pores in YBCO films by metal organic deposition (MOD) using tri-fluoroacetates (TFA). However, we have reported that a lot of non-reacted particles such as Y and Cu oxides were remained for the YBCO film surface grown by the precursors using Ba-poor solution. In this study, influences of YBCO growth rate on microstructures of the YBCO film were discussed to control microstructures of these second phase particles. As a result, microstructures of the YBCO film depended strongly on the YBCO growth rate, residues of Y and Cu oxides were dispersed randomly throughout the YBCO film grown at higher growth rate. Consequently, it was succeeded to control the segregated phases as seen in the previous YBCO film with Ba/Y = 1.5 at the film surface into the YBCO film. Jc of the YBCO film grown at higher rate was a value almost equal to that grown at previous growth rate.