A study was made of the formation energies of the simplest O defects in α-quartz, the O vacancy and interstitial, by using an ab initio approach which was based upon density functional theory in the local density approximation. The formation energies and entropies, and the migration paths and energies, were determined. It was concluded that O diffused, in quartz, via an interstitial mechanism. The interstitial had a dumb-bell structure, with one of the constituent atoms jumping towards a neighboring O site. The activation energy was equal to 4.7eV in the intrinsic regime, and to 2.8eV in the extrinsic regime.

Oxygen Self-Diffusion in α-Quartz. G.Roma, Y.Limoge, S.Baroni: Physical Review Letters, 2001, 86[20], 4564-7