Measurements were made of the release of radioactive Kr from neutron-irradiated single crystals at temperatures ranging from 150C to the melting point. In the higher-temperature region, it was assumed that the Kr diffused via an interstitial mechanism. At lower temperatures, a stronger temperature dependence of the Kr diffusivity was found. This was attributed to an interaction of the gas atoms with defects. The diffusivity of Kr at the melting point was 2.0 x 10-5cm2/s, and the data for higher temperatures could be described by:

D (cm2/s) = 1.6 x 10-3 exp[-0.31(eV)/kT]

The data for lower temperatures could be described by:

D (cm2/s) = 1.3 x 106 exp[-1.41(eV)/kT]

Rare-Gas Diffusion in Neutron-Irradiated Rubidium Halides. F.W.Felix: Physica Status Solidi B, 1968, 27[2], 529-34