The long-range diffusion was investigated, as a function of temperature, by monitoring the anelastic process due to the redistribution of D between compressed and dilated regions of the sample under an applied alternating stress of about 4Hz. The diffusion coefficient was found to obey the Arrhenius law at 200 to 390K; although deviations were observed at lower temperatures. The Arrhenius relationship was:

D (cm2/s) = 3.3 x 10-4 exp[-0.176(eV)/kT]

R.Cantelli, F.M.Mazzolai, M.Nuovo: Applied Physics, 1973, 1[1], 27-30