Concentration-dependent diffusion coefficients for 45Ca2+ in ion-exchanged NaCl were determined by using a sectioning method. Isothermal diffusion annealing was performed at temperatures ranging from 448 to 683C. The saturation diffusion coefficients, enthalpies and entropies of impurity-vacancy associations were calculated by using the common-ion model for the simultaneous diffusion of divalent ions in alkali halides. The saturation diffusion data could be described by:

D (cm2/s) = 1.14 x 10-3 exp[-0.851(eV)/kT]

H.Machida, W.J.Fredericks: Journal de Physique - Colloques, 1976, 7, 385-91