Physical and Optical Properties of Tellurium Dioxide-Based Quaternary Glasses: Potential for Nonlinear Optical Applications

An exploration was undertaken to examine the physical and optical traits of a quaternary glass system utilizing tellurium dioxide as its primary component. The glasses were prepared with 60TeO₂-15B₂O₃-(25−x)Bi₂O₃-xSrCl₂ molar composition, where x = 5 mol.%, 10 mol.%, 15 mol.%, and 20 mol.%. The utilization of x-ray diffraction interpretation verified the amorphous nature of the glasses. Several physical properties were measured, including density (ρ), molar volume (V_m), and oxygen packing density (OPD). It was observed that the density decreased (from 5.301 g/cm³ to 3.542 g/cm³) as the heavier molar mass of bismuth(III) oxide was replaced with the lighter molar mass of strontium chloride. Consequently, the glass matrix became less dense. The molar volume increased (from 40.129 cm³/mol to 51.612 cm³/mol) with higher strontium chloride content. Adding strontium chloride decreased the OPD (from 56.069 to 34.875), reducing the number of oxygen atoms in the glass sample. The optical properties were analyzed via the ultraviolet absorption spectrum. The cutoff wavelength (λ_c) decreased (from 442 nm to 359 nm) as the strontium chloride content increased. With increased strontium chloride content, the prepared glasses showed indirect transitions in their energy band gaps. Additionally, the values of the indirect band gap energy (E_opt) increased from 2.02 eV to 2.95 eV. The Urbach energy (ΔE), which characterizes the disorder in the glass structure, decreased (from 0.288 eV to 0.270 eV) with increasing strontium chloride concentration, indicating a lower defect concentration. The molar refractivity values ranged from 26.82 to 31.79, reflecting the polarizability of the constituent ions. The glasses demonstrated a metallization criterion within the range of 0.332 to 0.384, indicating their promise for applications in the area of nonlinear optical devices.

Spectra of optical absorption for the TBSr glasses.