Simple model for the nucleation of (001) and (100) oriented grains in YBCO films

A thermodynamical model, set up to describe the nucleation of vapour-deposited YBCO thin films, is reported. The role of the surface energy of YBCO nuclei is discussed. Information on the surface Gibbs energy of YBCO (100), (010) and (001) surfaces is obtained both from experimental results reported in the literature and from ab initio calculations. These data allow us to estimate the surface energy of the nuclei and to achieve a qualitative description of the crossover from (001) to (100) orientation at increasing supersaturation.