An investigation was made of the migration and solubility of He in Li-doped crystals. The results revealed the occurrence of interstitial diffusion and vacancy diffusion. The activation energy was equal to 1.16eV for impurities, and to 2.45eV for intrinsic vacancies. The corresponding dissolution activation energies were -0.50 and 0.81eV. Anomalously low values of the dissolution energy were attributed to the effect of a chemical interaction of He with Ca.

A.Y.Kupryazhkin, A.J.Kurkin: Fizika Tverdogo Tela, 1990, 32[8], 2349-53 (Physics of the Solid State, 1990, 32[8], 1363-6)