A 36NaCl tracer was placed on the surface of a crystal and was diffused into the specimen. The concentration profile was determined by using serial sectioning and radioactivity measurements. The diffusion of Cl ions in the pure material, for diffusion via vacancy pairs, could be described by:

D (cm2/s) = 4 x 103 exp[-1.8(eV)/kT]

The equivalent expression for diffusion via single vacancies was:

D (cm2/s) = 4 x 1019 exp[-4.0(eV)/kT]

Although the second values were anomalously high, this was suggested to explain the overall curvature of the Arrhenius plot.

Contributions from Vacancy Pairs and Single Vacancies to Chloride Impurity Diffusion in AgBr. A.P.Batra, L.M.Slifkin: Physica Status Solidi B, 1979, 93[1], K77-80