A kinetic semi-phenomenological analysis was made of diffusion processes, of the compensation effect (linear correlation between Arrhenius activation energy and pre-exponential factor), and of the relationship between diffusion and melting parameters. The model was based upon the kinetic many-body theory for thermally activated rate processes in solids. It took account of ps atomic and electronic phenomena which occurred in the vicinity (nm range) of the diffusing atom and which were synchronized with diffusion events with durations of 10-13 to 10-12s. It was found that an Arrhenius-like equation for the diffusion coefficient could be derived from the kinetics of the diffusion event, without involving equilibrium rate theory. The activation energy and pre-exponential factor could be expressed in terms of local parameters which characterized the ps atomic and electronic processes that were induced by short-lived high-energy fluctuations of diffusing atoms which occurred in their vicinity. The large range (about 5 orders of magnitude) of the observed variations in the pre-exponential factor was related to the observed variations in activation energy. The compensation effect was explained, and the coefficients in the linear correlation equation were expressed in terms of the melting point and entropy; in good agreement with experimental data.

Y.L.Khait, R.Beserman, D.Shaw, K.Dettmer: Physical Review B, 1994, 50[20], 14893-902