FTIR spectroscopy investigation of the crystallisation process in an iron rich glass

The crystallisation behaviour of an iron rich glass, obtained by recycling zinc hydrometallurgy waste, was investigated by FTIR spectroscopy. The transformations occurring in the glass subjected to different thermal cycles, i.e. liquid–liquid separation and crystallisation, were investigated by FTIR, XRD and TEM. The asymmetric SiOSi stretching vibration wave-number, 1016 cm−1 in the FTIR spectrum of the glass, increased with the heat treatment temperature and was related to the variation of the coefficient of thermal expansion and density of the glass-ceramic. The magnetite and pyroxene crystalline phase peak, at 638 cm−1, was utilised for determining the degree of crystallisation of the glass-ceramic by measuring the area of the peak as a function of the thermal treatment time; the results were compared with the same evaluation carried out by density measurements.