A modified electrostatic model for the diffusion of electropositive impurities in noble metals was developed by combining the assumptions which were made in the original LeClaire electrostatic model with those which were made in the Neumann-Hirschwald thermodynamic model for impurity diffusion. The calculations were based upon the 5-frequency model, and took account of a di-vacancy contribution at higher temperatures.

G.Neumann, V.Tölle: Philosophical Magazine A, 1995, 71[2], 231-47