Stress relaxation in electron bombarded silicate glasses

Abstract

In contrast to the behavior of vitreous silica which has developed internal stresses consequent upon nonuniform irradiation with ions (e.g., protons, deuterons, helium ions), the electron-bombarded vitreous silica does not show a post-irradiation stress relaxation. The complex silicate glasses which have been irradiated nonuniformly with electrons display large post-irradiation internal stress changes, which may be increases or decreases. It is evident that in them both positive and negative dilatation centers were formed and that they possess different annealing properties. It is not clear to what extent the internal stress changes found in these irradiated glasses are caused by annealing or by stress relaxation. Since plates which had been irradiated until they fractured did not appear to behave differently from unfractured samples, it is concluded that the stress changes are a microscopic rather than a macroscopic phenomenon. The reduced power dependence of the ionization compaction of vitreous silica on dose is discussed.