Synthesis, thermal, structural and linear optical properties of new glasses within the TeO2-TiO2-WO3 system

The glass-forming domain and physical properties, namely, the density, thermal, structural and linear optical properties of new glasses within the TeO2-TiO2-WO3 system have been investigated. By means of micro-Raman spectroscopy, the structure of these glasses was examined based on a full-scale spectral decomposition. The optical transmission and refractive index dispersion were measured by UV–Vis-NIR spectroscopy and spectroscopic ellipsometry respectively. Consistent correlations were established between the structural and linearoptical properties. Only minor structural modifications of the original TeO2-rich network are taking place upon adding TiO2 or WO3, suggesting the absence of Te–O–Te bond network depolymerization. Our results also suggest that, upon increasing TiO2 content, a phase separation occurs between amorphous TeO2-rich and amorphous TiO2-rich regions. We also argue that the structural trends upon adding WO3 evolve from uniformly dispersed WO6 octahedra (at low WO3 content) to amorphous WO3-like regions (at higher WO3 content) before the crystallization of γ-WO3 at 30 mol% of WO3. The compositional dependence of the refractive index and several optical constants (Urbach EU and dispersion Ed energies, oxide ion polarizabilities) is highlighted. These glasses collectively exhibit high refractive indices in the order of ~2.2.