A study was made of the diffusion of Ar in ion-bombarded single crystals with various vacancy concentrations. The results for diffusion between 20 and 300C were compatible with an interstitial diffusion mechanism which was largely independent of both vacancy and gas concentration. However, mobility via small vacancy clusters of constant size could not be excluded. The diffusion data could be described by:

D (cm2/s) = 105 exp[-1.5(eV)/kT]

Rare Gas Mobility in Pure and Doped Potassium Bromide. H.J.Matzke: Zeitschrift für Naturforschung, 1967, 22a[4], 507-18