Redox Equilibria of Multivalent Ions in Silicate Glasses

Experimental studies were made on the compositional dependence of the redox equilibrium of Eu in synthetic silicate liquids, together with an empirical model describing the observed compositional dependence. Electron paramagnetic resonance (EPR) was used to measure the concentration ratio of Eu 2+ to Eu 3+ in various glasses formed by rapidly quenching silicate liquids. The compositional field studied comprised mixtures of SiO 2 , TiO 2 , Al 2 O 3 , CaO, MgO, and Na 2 O. The proposed model describes the Eu 2+ /Eu 3+ ratio over the entire compositional field in terms of parameters easily related to each glass composition. The general applicability and utility of the model is further demonstrated by its application to the Fe 2+ ‐Fe 3+ , Ce 3+ ‐Ce 4+ , and Cr 3+ ‐Cr 6+ redox reactions in binary alkali oxide silicate glasses of Li, Na, and K.