Crystal-field effects in the diffusion of transition-metal ions in silver chloride

The diffusion in silver chloride of divalent vanadium, chromium, iron, cobalt, and nickel is shown to occur by means of vacancies. The high-temperature activation energy for diffusion of these first transition row solutes in AgCl is found to vary systematically with atomic number, dropping from 2.08 eV for V²⁺ to 1.18 eV for Mn²⁺ and then rising again to 1.88 eV for Ni²⁺. This variation can be quantitatively accounted for by the effect of the crystalline electric field on the d electrons during the solute-vacancy interchange.