Effect of in-situ reduction of Fe3 + on physical, structural and optical properties of calcium sodium silicate glasses and glass ceramics

Glasses and glass ceramics with composition of 45SiO2–25CaO–5P2O5–10Na2O–(15 − x)MnO2 − xFe2O3(x = 0, 5, 10 and 15) were prepared by melt-quenching technique. In the present work, the physical, structural and optical properties of these samples were investigated and correlated with the structural changes induced in the samples due to replacement of MnO2 with Fe2O3. Density and molar volume of the samples increased with Fe2O3 addition. Fe3 + is reduced to Fe2 + due to depleted presence of oxygen at 1550 °C in furnace and formed in-situ nano-crystalline phase in x = 10 and 15 samples, which enhanced the optical and structural stability of the samples. High Fe2O3 content prevented glass formation as observed in XRD results. The optical band gap decreases and sharpness of FTIR bands increases with Fe2O3 content. Highest refractive index and lowest Fermi energy is obtained for x = 15 sample.