Rutherford back-scattering spectrometry was used to measure the diffusion

constants of bromine in NaCl crystals at 20 to 600C. For crystals which had been

grown from the melt at 500C or above, the present data agreed well with published

data measured using other techniques. At about 450C, the activation energy fell

strongly; leading to a knee in the Arrhenius plot and surprisingly high roomtemperature

diffusion constants of ~2 x 10−16cm2/s. In case of crystals grown from

aqueous solution, cleavage led to a significant surface enrichment of Br on the

newly-formed surface, as compared to bulk composition. Thus, in such porous

crystals, Br could move several microns within minutes. Pre-annealing (500C, 3h)

prevented this surface enrichment. Diffusion constants in such pre-annealed

crystals were approximately the same as in melt-grown crystals.

Diffusion Constants of Br in NaCl Measured by Rutherford Backscattering

Spectroscopy. M.Hess, U.K.Krieger, C.Marcolli, T.Peter, R.H.Doremus,

W.A.Lanford: Journal of Applied Physics, 2009, 105[12], 124910