Absolute values of surface and step free energies from equilibrium crystal shapes.

It is shown that exact images of the three-dimensional equilibrium shape of crystallites (ECS), recorded at several temperatures between 0.3 and 0.8 of the melting temperature of a solid, can be evaluated to yield absolute values of the surface and step free energies versus temperature, in addition to the formation energy of kinks. The essential input for this novel approach is the temperature variation of the size of a facet on the ECS and of the separation between the Wulff point and that particular facet. This approach promises access to surface free energies over a large temperature range and for well-defined low-index surface orientations.