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. The diffusivity of Kr at the melting point was 4.5 x 10-6cm2/s, and the data for higher temperatures could be described by:

D (cm2/s) = 2.5 exp[-1.38(eV)/RT]

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