Investigation of the role of selenium (Se) metal on the structural, physical, and optical properties of lead phosphate glasses

Binary lead phosphate glasses (nine samples) containing different amount of selenium (Se) metal with chemical formula 40PbO–(60 − x) P₂O₅–xSe, (x = 0 (Se0)—15 (Se15)) in mol% have been successfully synthesized via melt quenching technique. The physical, optical, and FTIR spectroscopy for the prepared glass have been investigated. The density (D_s) of the investigated glasses increased from 5.38 ± 0.01 to 5.72 ± 0.01 g/cm³ and molar volume decreased from 32.30 ± 0.01 to 28.83 ± 0.01 cm³/mol for Se0 and Se15 samples, respectively. The free volume (V_f) and packing density (P_d) of all investigated glasses reduced with increasing Se ions in the glass networks. Vibrational modes confirm the significant depolymerization in the phosphate network with the addition of 40 mol% of PbO as well as different contents of Se ions. The indirect optical band gap (\(E_{g}^{Indirect}\)) decreased from 4.7 ± 0.01 to 2.25 ± 0.01 eV, whereas the direct band gap (\(E_{g}^{Direct}\)) decreased from 5.12 ± 0.01 to 3.10 ± 0.01 eV. The refractive index (n) and molar refraction (R_m) slightly increased as Se ions increased. Results confirm that the suggested glasses can be used in optical applications.