Development of novel ternary tellurite glasses for high temperature fiber optic mid-IR chemical sensing

The properties of novel ternary tellurite glasses, based on the TeO2–BaO–Bi2O3 system, are reported for their applications in on-line chemical sensing and process control by characterizing the fundamental frequencies of molecular vibrations in the 2–5 μm spectral region of mid-IR. The chemical sensing for process control also requires above room temperature operation (>100 °C) for prolonged periods of time. Bulk samples of ternary tellurite glasses with a number of different compositions were prepared using heavy molecular weight oxides of TeO2, BaO, and Bi2O3. Infrared and Raman spectroscopic analysis was carried out together with differential thermal analysis to study the relationship between glass structure and thermal and viscosity properties. The temperature dependence of the viscosities of the glasses is also reported. The compositional dependence of Raman frequency shifts and the corresponding change in the coordination of Te–O structure is discussed. The results from the IR edge, reflection spectroscopic, and wavelength dependence of refractive index are also reported.