Application of Mössbauer spectroscopy and FT-IR to describe coordination of amphoteric ions in structure of glasses from the SiO2–Na2O–MgO–CaO–Al2O3–Fe2O3 system

Abstract

Glasses from the SiO2-Na2O-MgO-CaO-Al2O3-Fe2O3 system include, among others, amorphous materials obtained by the vitrification of industrial slags, ashes, dusts, but also various hazardous wastes (e.g. asbestos) containing a high proportion of Al2O3 and Fe2O3 oxides in their basic composition. The main goal of the work was to evaluate the method of incorporation into the glass structure of amphoteric ions (Fe2+, Fe3+ and Al3+) incorporation into the glass structure and its effect on the glass viscosity. A mixture of 10 wt% and 12 wt% pure Fe2O3 powder and float glass cullet was melted in an electric furnace at 1450°C for 4 hours and then poured onto a steel plate. X-ray results confirmed the amorphous structure of all molten glasses. The viscosity of glasses was examined using linear dilatometry and high-temperature microscopy. Fourier transform infrared (FT-IR) and Mössbauer spectroscopy were used to study the coordination number of amphoteric ions and how they were incorporated into the glass lattice. The research confirmed that the increase in the share of amphoteric metal ions in the coordination number 4 causes the incorporation of these ions into the glass network. Metal ions Fe2+, Fe3+ and Al3+ occurring in tetrahedral coordination, depositing in the glass network next to Si4+ ions, strengthen the network and, as a result, can increase its viscosity in the range of forming temperatures.