Threshold energy of formation of an oxygen vacancy defect in SiO2 by atomic displacements using molecular dynamics

The interest on the effects of radiation in vitreous silica has increased recently due to its possible application as optical transmission component in fusion reactors. This material will be exposed to high neutron irradiation fluxes during operation that can change its mechanical and optical properties. In this paper, we present molecular dynamics simulations of defect production in amorphous silica. In particular, we study the minimum energy required to generate a stable oxygen vacancy by atomic displacements. A range of energies that differs significantly depending on the initial displaced atom being silicon or oxygen is presented. We show that an oxygen recoil is able to easily generate stable oxygen vacancies while a silicon recoil requires much higher energies to produce stable oxygen vacancies.