Oxygen self-diffusion in alpha-quartz

Ab initio calculations based on density functional theory (DFT) and local density approximation (LDA) were used to study the formation energy of the oxygen defects in α-quartz, oxygen vacancy and interstitial oxygen. The calculations were performed at zero pressure, relaxing atomic position, volume and cell shape by conjugate gradient method keeping orthorhombic symmetry. The results suggested that oxygen diffused into quartz by an interstitial mechanism such that one of the constitutive atoms jumped towards a neighbouring oxygen site.