The serial sectioning technique was used to study the diffusion of Na in pure NaCl. The data, for temperatures ranging from 590 to 690C, could be described by:

D (cm2/s) = 3.2 exp[-1.78(eV)/kT]

A comparison with ionic conductivity data revealed an excess diffusion of 10 to 20%. This was tentatively attributed to the effect of vacancy pairs.

Self-Diffusion of Na in NaCl. H.L.Downing, R.J.Friauf: Journal of Physics and Chemistry of Solids, 1970, 31[4], 845-7

Table 131

Isotope Effect for Na Diffusion in NaCl