60Co γ-ray-induced intrinsic defect processes in fluorine-doped synthetic SiO2 glasses of different fluorine concentrations

Fluorine-doped synthetic SiO2 glass is suitable for investigating intrinsic defect processes in SiO2 glass because of the high radiation hardness and the low concentrations of defect precursors such as the strained Si-O-Si bonds and impurity-related network modifiers including SiOH, SiH, and SiCl groups. When the concentrations of the defect precursors are minimized by moderate fluorine doping into SiO2 glass, formation of oxygen vacancy-interstitial pairs (Frenkel pairs) is the primarily Co-60 gamma-ray-induced defect process. However, heavy fluorine doping tends to degrade the radiation hardness and enhance the formation of the silicon and oxygen dangling bonds, suggesting the presence of another type of defect precursors in heavily fluorine-doped SiO2 glasses. (C) 2008 Elsevier B.V. All rights reserved.