An investigation was made of the kinetics of inert gas release from undoped and U-doped (0.05at%U) single crystals, following irradiation to an integrated thermal flux of about 1016/cm2, using charcoal traps in a vacuum apparatus and activity measurements of the released gas. The 133Xe diffusion results for temperatures ranging from 700 to 1100C could be described by:

D (cm2/s) = 1 x 107 exp[-3.5(eV)/kT]

It was suggested that the rare gas atoms moved independently of both ions of the host lattice, and made use of those diffusion sites (interstitial sites) which were available in the highest concentration.

Rare Gas Diffusion in Alkaline-Earth Fluorides (Kr, Xe in SrF2, BaF2). F.W.Felix, S.Y.T.Lagerwall: Physica Status Solidi B, 1969, 33[1], 85-9

Table 156

Arrhenius Parameters for Interdiffusion

in the BaF2-SrF2 System at 1033 to 1238C