The structure of sodium iron silicate glass - a multi-technique approach

Sodium iron silicate glasses of formula 0.3Na(2)O . xFe(2)O(3).(0.7-x)SiO2 (0.0 less than or equal to x less than or equal to 0.20) have been prepared by melt-quenching and their structures have been studied using X-ray photoelectron spectroscopy (XPS), neutron diffraction and Mossbauer spectroscopy. XPS of surfaces fractured in ultra-high vacuum showed the presence of both Fe2+ and Fe3+ in the glasses but the proportion of the smaller oxidation state is