Engineering of TeO₂-ZnO-BaO-Based Glasses for Mid-Infrared Transmitting Optics

In this paper, the glass systems, TeO₂-ZnO-BaO (TZB), TeO₂-ZnO-BaO-Nb₂O₅ (TZB-Nb) and TeO₂-ZnO-BaO-MoO₃ (TZB-Mo), were fabricated by the traditional melt-quench protocol for use as mid-infrared (mid-IR) transmitting optical material. The effect of Nb₂O₅ and MoO₃ on the key glass material properties was studied through various techniques. From the Raman analysis, it was found that the structural modification was clear with the addition of both Nb₂O₅ and MoO₃ in the TZB system. The transmittance of studied glasses was measured and found that the optical window covered a region from 0.4 to 6 μm. The larger linear refractive index was obtained for the Nb₂O₅-doped TZB glass system than that of other studied systems. High glass transition temperature, low thermo-mechanical coefficient and high Knoop hardness were noticed in the Nb₂O₅-doped TZB glass system due to the increase in cross-linking density and rigidity in the tellurite network. The results suggest that the Nb₂O₅-doped TZB optical glasses could be a promising material for mid-infrared transmitting optics.