Structure-property correlations in TiO2-Bi2O3-B2O3-TeO2 glasses.

Tellurite and borotellurite glasses containing Bi 2 O 3 and TiO 2 were prepared and structure-property correlations were carried out by density measurements, X-ray diffraction, Differential Scanning Calorimetry (DSC), Raman, FTIR, UV–visible and 11 B MAS-NMR studies. Titanium-tellurite and titanium bismuth tellurite glasses require high melt-cooling rates and were prepared by splat quenching. On adding B 2 O 3 , the glass forming ability (GFA) enhances considerably and bulk glasses could be synthesized at lower quenching rates. The density of glasses shows a direct correlation with molecular mass of the constituents. UV–visible studies were used to determine the optical band gap and refractive index. Raman studies found that the co-ordination number of tellurium ions with oxygen (N Te O ) remains constant with variation in TiO 2 molar content, while the incorporation of B 2 O 3 and Bi 2 O 3 decreases N Te O . DSC studies show that the glass transition temperature (T g ) increases with B 2 O 3 and TiO 2 concentrations and that T g correlates well with bond enthalpy of the metal oxides. 11 B MAS-NMR studies found that the co-ordination number of boron with oxygen (N B O ) decreases with increase in B 2 O 3 content while increasing TiO 2 and Bi 2 O 3 concentration does not significantly modify N B O . [ABSTRACT FROM AUTHOR]