The nature of fluorine in amorphous silica

Abstract

We have used solid-state nuclear magnetic resonance spectroscopy and molecular dynamics simulations to characterize the short-range structure of fluorine-doped silica glass. The fluorine atoms in a glass containing 3 wt% fluorine are found in two different structural environments. The most abundant of these is a fluorine atom bonded to a tetrahedral silicon atom, where the fluorine has replaced one of the bridging oxygens and formed the usual Q 3 species. The second, and less abundant of these fluorine types, originates from fluorine bonded to a silicon atom with four bridging oxygen atoms, ultimately giving rise to a fivefold coordinated silicon atom. Additional insight into these Si–F bonding configurations was obtained in the simulation results.