Structural and Optical Properties of Li₂O–NaF–ZnO–P₂O₅:(CdO + S) Glass System

Glasses having composition 5Li₂O-33NaF-7ZnO-55P₂O₅: x wt% (CdO + S) where x = 0.0, 1.0, 2.0, 3.0 and 4.0 wt%, were prepared by the melt quenching method and their amorphous nature was confirmed by X-ray diffraction technique. Variations in density (ρ), molar volume (V _m) and glass transition temperature (T _g) have been correlated with structural changes in the glass matrix. The optical absorption spectra of the polished samples were recorded in spectral range from 200 to 1000 nm at room temperature. The optical band gap (E _opt.) and Urbach energy (ΔE) were determined from the absorption spectra. These parameters (E _opt., ΔE) were found to vary depending on the composition of the glasses. The Fourier-transform Infrared (FTIR) spectra have been recorded in the spectral range from 400 to 4000 cm^–1. The FTIR reveals that the addition of Cd²⁺ ions provide ionic cross-linking between the non-bridging oxygen of different chains and increasing the bond strength of this ionic cross-link which confirmed by decrease in the molar volume and increase in the glass transition temperature when (CdO + S) content is increased. The compositional dependences of the above properties are discussed and correlated with the structural changes in glass matrix.