The diffusivity of the Cr2+ ions was measured by using conventional serial sectioning and radio-tracer techniques. The activation energy for diffusion, at temperatures ranging from 325 to 440C, was equal to 1.25eV. The high-temperature activation energy was found to be related to the number of electrons in the d-shell. The migration energy could be quantitatively accounted for in terms of the electronic contribution to the ion energy, in the normal and activated positions, resulting from crystal-field splitting.

A.P.Batra, J.P.Hernandez, L.M.Slifkin: Physical Review Letters, 1976, 36[15], 876-8