Sn2+ - Sn4+ and Fe2+ - Fe3+ redox interaction in 30 Na2O—70 SiO2 glass

Abstract

The role of stannous tin as a temperature-dependent reducing agent in a 30 Na2O—70 SiO2 glass containing Fe2+ and Fe3+ ions was investigated at 550 and 650 °C and different treatment times. The proportions of Fe2+ and Sn4+ ions were found to increase following a decrease in Sn2+ and Fe3+ contents during Sn2+ - Sn4+ and Fe2+ - Fe3+ mutual redox interaction on thermal treatments. These quantitative results obtained for the first time in a silicate glass were discussed for the redox pairs Sn2+ - Sn4+ and Fe2+ - Fe3+ in the light of standard reduction potentials of 0.15 and 0.77 eV, respectively, in aqueous solutions.