EFFECTS OF NITROGEN AND CARBON ION-IMPLANTATION ON DEVITRIFICATION OF SILICA GLASSES

The effects of nitrogen and carbon ion implantation on devitrification of stoichiometric and oxygen deficient silica glasses were investigated. Linear crystal growth was observed in stoichiometric silica glass and was not affected by ion implantation. Parabolic crystal growth was observed in oxygen-deficient glasses, which was retarded by ion implantation, with the rate of crystal growth retardation being greater for nitrogen implantation than for carbon implantation. Activation energy for parabolic rate constant for crystal growth was about similar to 105 kcal/mol. When the oxygen-deficient silica glasses were hydrated, their crystal growth became linear and the activation energies were smaller. The reduction in activation energy by hydration was approximately equal to the activation energy for water diffusion in silica. It is suggested that nitrogen ion implantation decreased the crystal growth rate in the oxygen-deficient glasses by forming an oxynitride layer, which is an effective water diffusion barrier.