Optical studies of mutual redox and partitioning of coordination sites between Ce3+/Ce4+ and Fe2+/Fe3+ ions in Na2O–CaO–SiO2 glass
Tarja Volotinen, İlknur Bayrak Pehlivan
Abstract
The absorption spectra of the Fe– and Ce–doped 15Na2O–15CaO–70SiO2 glasses (mol%), melted in oxidising and reducing conditions, have been analysed. A repeatable set of the fitting parameters has been developed for the Ce3+ and Ce4+ ions, while previously published parameters were used for the Fe–ions. The Ce–ions significantly decrease the proportion of Fe2+ions in both electric– and gas–melted glasses, and the Ce3+ ions content increases due to the mutual redox between Fe and Ce, most effectively in reduced glasses. The Fe3+ ions in octahedral sites decrease and in tetrahedral sites increase. The photoluminescence (PL) emission spectra (excited at 355 nm laser) confirmed the changes between the Fe3+ and Ce3+ ions at low concentrations. The PL emission of the Fe3+ ions is very weak and may come from the tetrahedral sites. The Ce3+ emission peak was strong and consist of four components.