Effects of silver ion exchange and subsequent treatments on the UV–VIS spectra of silicate glasses. I. Undoped, CeO2-doped, and (CeO2 + Sb2O3)-codoped photo-thermo-refractive matrix glasses

The effects of the silver ion exchange and of subsequent UV irradiation and/or heat treatment on the optical density spectra of photo-thermo-refractive matrix glass samples both virgin and doped with cerium and/or antimony oxides were investigated. The incorporation of silver by ion exchange for ~ 15 min at 310 °C was found to cause, for all glasses except those with CeO2 content around 0.1 mol% or more, a shift of the UV limit of strong absorption to the greater wavelengths by ~ 70–100 nm due to the occurrence of Ag+-related absorption. Complicated changes caused by the UV irradiation and/or heat treatment of ion-exchanged samples in the location of their UV limit of strong absorption and in the absorption throughout the 330–550 nm region were analyzed and shown to be greatly influenced by (i) the kind of dopant(s), (ii) chances for shifting the redox and other equilibria involving the dopants at temperatures of particular treatment processes, and (iii) NaBr presence in the glass batch composition. The effect of NaBr addition was explained tentatively in terms of formation, after the heat treatment, of AgBr clusters or nanocrystals.