Oxygen species in SiO2: a first-principles investigation

Using a density functional approach, we determine the relative stability of various oxygen species in alpha -quartz. We considered interstitial specie s in the form of atomic and molecular oxygen, as well as network species, s uch as peroxyl and ozonyl link-ages. The interstitial molecular oxygen spec ies is found to be the most stable one. The ozonyl link-age lies higher in energy by 1.0 eV. Dissociation of the interstitial O-2 molecule into two pe roxyl linkages or into two interstitial oxygen species occurs at even highe r energies (1.6 and 3.2 eV respectively). These results favor a long-range diffusion mechanism based on the interstitial O-2 molecule. (C) 2001 Elsevi er Science B.V. All rights reserved.