Structural and optical modifications in sodium zinc-based phosphate glass upon substitution of Na2O with Fe2O3

In this study, Fe2O3 was introduced into sodium zinc-based phosphate glass, replacing Na2O. Using the conventional melt quenching technique, a glass system with the chemical composition 45P(2)O(5) - 34ZnO - (21-x) Na2O - xFe(2)O(3) (where, x = 1, 2, 3, 4, and 5 mol%) was prepared. X-ray diffraction (XRD) analysis showed that this substitution did not alter the glass's amorphous structure. However, the density increased slightly, potentially due to the higher molecular mass of Fe2O3 compared to Na2O. This density change suggests a possible alteration in the glass's optical properties. Optical measurements revealed a shift towards the red spectrum and a decrease in transmittance, particularly at 543 nm, indicating increased optical loss. This loss was attributed to increased reflectance, not absorption. The optical band gaps decreased with higher Fe2O3 content, enhancing the glass's optical resistance, and making it suitable for applications like optical filters and shielding materials. The optical loss tangent analysis showed that the material's efficiency in transmitting electromagnetic energy decreased with Fe2O3 substitution, likely due to changes in the electronic structure. The study also noted that Fe2O3 improved optical absorption, as demonstrated by the Hydrogenic Excitonic Model (HEM).