Radiation hardening in sol-gel derived Er³⁺-doped silica glasses

The aim of the present paper is to report the effect of radiation on the Er³⁺-doped sol-gel silica glasses. A possible application of these sol-gel glasses could be their use in harsh radiation environments. The sol-gel glasses are fabricated by densification of erbium salt-soaked nanoporous silica xerogels through polymeric sol-gel technique. The radiation-induced attenuation of Er³⁺-doped sol-gel silica is found to increase with erbium content. Electron paramagnetic resonance studies reveal the presence of E′_δ point defects. This happens in the sol-gel aluminum-silica glass after an exposure to γ-rays (kGy) and in sol-gel silica glass after an exposure to electrons (MGy). The concentration levels of these point defects are much lower in γ-ray irradiated sol-gel silica glasses. When the samples are co-doped with Al, the exposure to γ-ray radiation causes a possible reduction of the erbium valence from Er³⁺ to Er²⁺ ions. This process occurs in association with the formation of aluminum oxygen hole centers and different intrinsic point defects.