Measurements were made of the release of 41Ar and 39Ar from fast neutron-irradiated (greater than 1019/cm2) single crystals. Diffusion at temperatures ranging from 425K to the melting point occurred via an interstitial mechanism. The diffusivity at the melting point of 1134K was 10-5cm2/s. The results for temperatures ranging from 425 to 1134K could be described by:

D (cm2/s) = 3 x 102 exp[-1.8(eV)/kT]

F.W.Felix: Proceedings of the British Ceramic Society, 1967, 9, 273-7