The serial sectioning technique was used to study the diffusion of 22Na+ in single crystals. The data, for 450 to 750C, could be described by:

D (cm2/s) = 33.16 exp[-1.975(eV)/kT]

in the intrinsic range, and by:

D (cm2/s) = 1.585 x 10-3 exp[-1.244(eV)/kT]

in the extrinsic range.

The results showed that the diffusion of the ions involved 2 mechanisms; one of which characterized the intrinsic regime and the other the extrinsic regime.

Effect of the Radius of an Ion on its Diffusion into NaCl Single Crystals. F.Bénière, M.Bénière, M.Chemla: Journal de Chimie Physique et de Physicochimie Biologique, 1969, 66[5], 898-902