Reactivity of SiCl and SiF groups in SiO2 glass with mobile interstitial O2 and H2O molecules

Reactions of common network-bound halogens in synthetic SiO2 glass, SiCl and SiF groups, with interstitial O-2 and H2O molecules incorporated by thermally annealing were studied. It was found that the chemical properties are distinctly different between SiCl and SiF groups. SiCl groups react with interstitial O-2 and H2O to form interstitial Cl-2 and HCl, respectively. In contrast, formation of interstitial F-2 and HF due to the reaction of SiF groups with interstitial O-2 and H2O is not observed. The reactivity of SiCl and SiF groups is in accord with the properties and thermodynamic data of their respective analogous compounds, SiCl4 and SiF4. (c) 2007 Elsevier B.V. All rights reserved.