Structural, Spectroscopic, and Optical Properties of Na2O–SiO2 Glass Network Doped with Er2O3

Abstract

A glass series of (45-x) Na₂O-55SiO₂-xEr₂O₃, with x ranging from zero to 10 mol%, was produced via the melt-quenching technique. The study was focused on the modification in the glass structure to improve the optical and spectroscopic characteristics. Non-bridging oxygens (NBOs) are created within the SiO₄ tetrahedra, with the predominant f₁ and f₂ modes. The incorporation of 2% Er₂O₃ into the network elevated f₁ fraction from 0.46 to 0.68, which subsequently decreased with an increase in Er³⁺ ions to 0.5. The glass density (D) of the base sample was 2.478 g/cm³, which increased to 3.433 g/cm³ with the addition of Er₂O₃. The molar volume (V_m) values increased from 24.951 to 27.203 cm³/mol, depending on the ratio of Er³⁺ ions. The optical band gap (E_g) values dropped from 3.168 eV to 2.183 eV as the Er₂O₃ concentration rose from zero to 10 mol%, while the refractive index (n_o) increased from 2.353 to 2.661. The spectroscopic properties were analyzed utilizing Judd–Ofelt theory. The intensity parameters (Ω_λ) exhibit the order Ω₂ > Ω₄ > Ω₆ for all samples containing Er³⁺ ions, due to the high covalent character of the glass. Moreover, the Ω_λ is dependent on the concentration of Er₂O₃; Ω₂ decreased from 1.159 to 0.373, Ω₄ decreased from 0.851 to 0.247, and Ω₆ varied from 0.501 to 0.209, as the Er₂O₃ concentration increased from 2 to 10 mol%. The computed radiative lifetime rose from 85.027 to 146.177 µs, rendering these glasses appropriate for use as a laser active medium.