The migration of the small homovalent cation in monocrystalline material was studied by using 42K tracer/sectioning methods. It was found that the results could be described by:

D (cm2/s) = 4.70 x 101 exp[-35.30(kcal/mol)/RT]

S.M.Klotsman, I.P.Polikarpova, G.N.Tatarinova, A.N.Timofeev: Physical Review B, 1988, 38[11], 7765-76