Theory of orientation textures due to surface energy anisotropies

The effect of surface free energy on the orientation of nuclei on a substrate is examined. In general, the orientation of the nuclei is not determined by minimizing the nucleus-substrate interfacial free energy alone: all interfacial anisotropies must be considered. That orientation preferences should result from anisotropies in the substrate-nucleus interfacial free energies is obvious, but we find that strong orientation effects are present even if this energy is assumed to be independent of the nucleus orientation, provided that the nutrient-nucleus interfacial free energies are anisotropic. Furthermore, varying the magnitude of even an isotropic nucleus-substrate energy will change the orientation of the nuclei. The theory points to some simple rules for prediction of nucleation orientations.