Optical spectroscopy of sodium silicate glasses prepared with nano- and micro-sized iron oxide particles

Wet chemical analysis and UV-VIS spectroscopy methods were used to determine the oxidation state of iron in Na2O•2SiO2 glasses, containing 0.3 mol% of Fe2O3 . The oxidation state of iron in the sodium silicate glasses was varied by changing the size of iron oxide particles used for preparation of glass batches and the melting temperature. In sodium silicate glasses iron commonly exists as an equilibrium mixture of ferrous ions, Fe2+, and ferric ions Fe3+. The increase of the melting temperature led to the transformation of ferric ions to ferrous ions. It was also shown that in the glasses prepared from nano-sized iron oxide particles the Fe2+/Fe3+ equilibrium ratio is lower (i.e. smaller amount of ferrous ions were formed) comparing to that in the glasses prepared from micro-sized iron oxide particles.