Helium diffusion in α-quartz and vitreous silica was studied by means of molecular dynamics. It was shown that, as the temperature increased, the motion of a helium atom in crystalline quartz changed from vibratory motion around the equilibrium position at 300K, to free displacements throughout the bulk of the crystal at 750K. It was demonstrated that even an insignificant number of structural defects increased the helium mobility.

Migration Paths of Helium in α-Quartz and Vitreous Silica from Molecular dynamics Data. Boiko, G.G., Berezhnoi, G.V.: Glass Physics and Chemistry, 2003, 29[1], 42-8