An investigation was made, of the diffusion of Tl+ in single crystals, by using serial sectioning and fluorescence analysis. An investigation was also made of diffusion in a thermal gradient, but it was found that the rate of thermal diffusion was insignificant when compared to normal diffusion. It was found that the data, for temperatures ranging from 225 to 400C, could be described by:

D (cm2/s) = 4.8 x 10-9 exp[-0.37(eV)/kT]

The data for temperatures ranging from 400 to 635C could be described by:

D (cm2/s) = 5.3 x 10-3 exp[-1.17(eV)/kT]

Distribution of Impurity Ions in Ionic Crystals (Tl in NaI) by Controlled Diffusion. K.Schmidt, H.Staude: Zeitschrift für Physikalische Chemie, 1968, 60[1-4], 90-113