Physical, structural, and optical characteristics of the glasses system based on lanthanum-doped phosphate

The formation of phosphate glasses, whose chemical composition is (65-x) P₂O₅–15 Li₂O–15 ZnO– 5Bi₂O₃–xLa₂O₃, was achieved by a rapid melt-quench procedure plus casting. Raising the quantity of La³⁺ in glasses causes a drop in molar volume and a corresponding rise in density. FTIR spectroscopy has been employed to investigate the structural modifications resulting from La³⁺ doping. A reduction in bond angles and the shrinking the structural framework of the polymerized network are the reasons behind numerous new behaviors observed when the dopant La³⁺ content of phosphate glass is increased. UV–visible-NIR measurements revealed a redshift in the optical absorption edge toward higher wavelengths and a reduction in the magnitude of an optical energy gap (E_g). The direct optical gap (E_g) decreased from 4.005 to 3.926 eV, whereas the corresponding indirect optical gap (E_g) decreased from 3.81 to 3.62 eV. Non-bridging oxygens (NBOs) have been shown to be the source of the decrease in E_g. The nonlinear optically susceptibilities (χ), nonlinear coefficient of refraction (n₂), and optically refractive index (n₀) all increase as the quantity of La³⁺ rises, whereas the metallization criterion(M) and molar refraction (R^molar) computation indicates declining values as the quantity of La³⁺ ions rise in the glass structure. Photoluminescence spectra of La₂O₃ doped phosphate glass carried at an excitation wavelength of 220 nm which exhibit emission peaks at 243, 260, and 275 nm in UV region.