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 temperatures of 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