A theory was developed for diffusion of interstitial impurities in the diamond lattice. For ionized impurities the theory was based on a model in which the interaction of the ion with the host atoms was given by an attractive potential produced by the polarization of the host atoms, and a repulsive potential due to overlap of nonbonding electrons. The interaction energy was calculated at two interstitial positions of symmetry, and the activation energy for diffusion was taken as the difference between the two. Good agreement with experiment was found for lithium, copper, and silver. The theory predicted an optimum impurity size for diffusion, and thus explains the great diffusivity of copper. It also claims that the interstitial position of lithium and copper was not one of tetrahedral symmetry.

Theory of Diffusion and Equilibrium Position of Interstitial Impurities in the Diamond Lattice. Weiser, K.: Physical Review, 1962, 126[4], 1427-36