Single crystals with an initial impurity content of less than 1ppm were used, and the diffusion profiles were determined by means of radiotracer and sectioning techniques. Transition metal diffusion (table 33) occurred via vacancies, and the results for temperatures of between 325 and 440C indicated an activation energy of 1.25eV.

Crystal-Field Effects in the Diffusion of Transition-Metal Ions in Silver Chloride. A.P.Batra, J.P.Hernandez, L.M.Slifkin: Physical Review B, 1980, 22[2], 734-42. See also: Physical Review Letters, 1976, 36[15], 876-8