Iron oxide-doped alkali-lime-silica glasses Part 2. Voltammetric studies

Abstract

Alkali-lime-silica glass melts doped with different quantities of Fe2O3 in the range of 0.1 to 2 mol% were studied by means of square-wave voltammetry. At low iron concentrations a one-step reduction of Fe^III to Fe^II was observed. The shift of the standard potential with the alkali concentration is explained using a structural model where FeIII occurs as a tetrahedrally coordinated complex which forms an ion pair with an alkali cation. At higher Fe2O3 quantities a two-step reduction was observed. This means that FeIII-containing compounds occur as two thermodynamically different species. In agreement with the EPR-spectroscopic behaviour, this was explained by the formation of iron-containing clusters.