THERMODYNAMICS AND KINETICS OF SURFACE-AREA CHANGES OF FACETED PARTICLES

An equation is derived that describes the influence of particle size a nd shape on the free energies of particles of anisotropic specific sur face free energies. When the specific surface free energy is isotropic , the general equation reduces directly to the Gibbs-Thomson equation for the chemical potential of spherical drops and predicts the accepte d driving force for neck growth between two spherical particles. The g eneral equation is also used to obtain equations for the chemical pote ntials of particles of nonequilibrium shapes and to derive alternate r ate equations for different possible rate-controlling steps of mass tr ansport when faceted {100} ridge/channel arrays etched into a {100} si ngle-crystal surface decrease in depth to reduce the surface free ener gy. Edge free energies are suggested to sometimes play important roles in determining the sequence of shape changes that occur when particle s of nonequilibrium shapes are annealed.