Equilibrium crystal shapes: towards absolute energies

An increasing number of investigations are focussing on the equilibrium shapes of 2D and 3D crystallites that are being imaged at high resolution by scanning electron probes. Features, such as facets and vicinal surfaces on 3D equilibrium crystal shapes (ECS), are of particular interest since they offer a route towards the evaluation of relative step-formation and step-interaction energies. It is shown that a measurement of the temperature dependence of the ECS, in particular of facet shapes and sizes, can be used to extract absolute step and surface free energies. This novel approach appears to be capable of providing surface free energies over a sufficiently large range of temperatures, such that an extrapolation to even 0 K can be done. Thus, a meaningful comparison of experimental and theoretical surface energies comes into view. (C) 2001 Elsevier Science Ltd. All rights reserved.