Effect of Increasing Fe2O3 Content on the Structural, Thermal, and Optical Characteristics of Soda–Lime–Silica Glass-Ceramics

In this study, a series of xFe2O3–Na2O–CaO–SiO2 glass-ceramics containing 0–28 wt.% Fe2O3 were prepared via the conventional melt-quenching technique. The resulting samples, designated S1–S4, were subsequently subjected to thermal treatment and investigated with respect to their structural, thermal, and optical characteristics. Differential scanning calorimetry analysis revealed the influence of the Fe2O3 concentration on the glass transition temperature and crystallization behavior of the samples. Structural analysis of the samples revealed that crystalline silicate and iron oxide phases constituted the predominant crystalline phases, with their overall crystallinity being strongly dependent on the Fe2O3 content and thermal treatment. Fourier transform infrared spectroscopy evidenced structural modifications of the silicate network induced by iron incorporation, while ultraviolet–visible–near infrared spectroscopy highlighted the presence of Fe2+/Fe3+ ions and their associated electronic transitions. The results indicate that increasing the Fe2O3 content significantly affects the network structure, redox state, and thermal behavior of the glass-ceramic system, leading to enhanced absorption properties.