Defects and optical absorption bands induced by surplus oxygen in high‐purity synthetic silica

TLDR: In this article, the authors investigated the nature of excess oxygen in as-manufactured and γ-irradiated high-purity synthetic silicas and found that the excess oxygen exists in the glass in two forms: as peroxy linkages and as interstitial molecular oxygen.

Abstract: The nature of excess oxygen in as‐manufactured and γ‐irradiated high‐purity synthetic silicas is investigated. Electron‐spin‐resonance measurements suggest that peroxy radicals ( 3/4 SiOO⋅) could be produced either by the cleavage of peroxy linkages ( 3/4 SiOOSi 3/4 ) or by the reaction of E’centers ( 3/4 Si⋅) with oxygen molecules. The excess oxygen is found to exist in the glass in two forms: as peroxy linkages and as interstitial molecular oxygen. The peroxy linkage is shown to be the cause of optical absorption at 3.8 eV. Heat treatment at 900–1000 °C results in the growth of the 3.8‐eV band, that is, the peroxy linkages, through the reaction of oxygen vacancies and interstitial dioxygen molecules. These results indicate that the 5.0‐ and 3.8‐eV bands (which are characteristic of ‘‘oxygen‐deficient’’ and ‘‘oxygen‐surplus’’ silica, respectively) can coexist in a glass, depending on the synthesis conditions.