A serial sectioning technique was used to study the self-diffusion of 22Na in high-purity crystals in the extrinsic range. The data for temperatures below 550C could be described by:

D (cm2/s) = 3.55 x 10-6 exp[-0.84(eV)/kT]

It was concluded that, even in pure crystals, there were still enough cation vacancies (some 10-6mol%) to account for single cation vacancy migration.

R.Reisfeld, W.J.Fredericks: Israel Journal of Chemistry, 1971, 8[6], 959-62

The best linear fits to the solute diffusion data ([382] to [383], [391] to [397], [403] to [405]) yield:

Cs: Ln[Do] = 0.29E – 9.9 (R2 = 0.73); Na: Ln[Do] = 0.57E – 22.4 (R2 = 0.99);

Sr: Ln[Do] = 0.55E – 20.5 (R2 = 0.51)