Microstructure and crystallization properties of TeO₂-PbF ₂ glasses

The microstructures of (1 - x)(TeO₂)-xPbF₂, (x = 0.1, 0.15, and 0.25 mol) glasses were investigated by using the Raman spectroscopic technique. The effect of compositions on the TeO₂ glass networks and the intensity ratios of the deconvoluted Raman peaks were determined. The results confirm that the addition of modifiers to the glass network former shifts the Raman intensity and the peak wavenumber values for each band in the 167-165, 652-645, and 747- 755 cm^-1 wavenumber regions. The structural evaluation was recognized from the Raman spectra, with the structural units described as [TeO₃₊₁] polyhedra, [TeO₃] trigonal pyramids, and [TeO₄] trigonal bipyramids for this binary glass system. Heat-treatment of the samples shows that the metastable crystalline phase of TeO₂ known as γ-TeO₂ is formed only when the modifier content is 10 mol% in the glass matrix. Transparent glass properties were not realized when the TeO₂ amount was decreased to less than 10 mol% content.