The results of first-principles quantum mechanical calculations of energetic parameters of vacancies, interstitials, gas atoms (H, He) and some small point defect complexes in beryllium were presented. It was found that the most energetically favourable position for self-interstitial was the basal octahedral one, for hydrogen atoms was the basal tetrahedral, while He atoms could be located with equal probability in basal octahedral and basal tetrahedral interstitial positions. The formation of divacancies and tri-vacancies from individual vacancies was shown to be energetically unfavourable, which implies high stability of beryllium against vacancy clustering. The preliminary estimates of diffusion pathways for H and He interstitials indicate essential differences: while hydrogen diffusion was nearly isotropic, that of He occurs preferentially in basal planes with the migration energy of only 0.1 eV.

Vacancies, Interstitials and Gas Atoms in Beryllium. M.G.Ganchenkova, P.V.Vladimirov, V.A.Borodin: Journal of Nuclear Materials, 2009, 386-388, 79-81