Crystal growth process of Y123 film fabricated by modified TFA-MOD process

Modified metal-organic deposition (MOD) process using precursor solution of trifluoroacetates (TFA) for Y and Ba and F-free salt for Cu is one of the most promising low cost non-vacuum methods to fabricate the coated conductor of YBa₂Cu₃O_7-X (Y123) film with high critical current density. Since Y123 phase grows in the precursor film by the release of HF with supplying H₂O, liquid/gas evolution affects the growth process, microstructure and properties of Y123 film. However, details of the growth mechanism of Y123 crystals are still unknown. To clarify the growth mechanism of Y123 film, the growth process of Y123 crystal was studied by the experimental method and the numerical method (FDM analysis). The quenching experiments during the growth of Y123 crystals on LaAlO₃ (LAO) and/or CeO₂/LAO substrates revealed the microstructures of growing Y123 crystals through TEM observations. The growth model for Y123 crystals in YBCO film with some process-controlling parameters was obtained on the basis of the experimental results. The growth processes of faceted Y123 crystals with various crystal orientations were simulated by the two-dimensional numerical method using c-axis and a-axis growth rate functions, and the effects of initial distributions of nucleated crystals and particles were discussed.