Viscosity of titania-bearing sodium silicate melts

Viscosity measurements made between 102 and 1012 dPa s are reported for six (25 − x)Na2O · xTiO2 · 75SiO2 glasses (x = 0, 1, 2.5, 5, 7.5 and 10). The methods of falling ball, rotational viscosimetry and dilatometric axial deformation rate measurement were used to cover the studied viscosity range. The values of dilatometric glass transition temperature are also reported. ed temperature and compositional dependencies of viscosity confirmed the validity of the Adam-Gibbs viscosity equation. The individual molar free hindrance energies Be and the configurational entropies Sconf(Tg) resulted from the least-squares regression treatment for each glass composition. he molar free hindrance energies and the configurational entropies depend on the TiO2 content in a similar fashion, indicating the changes in the titanium structural role in the compositional range studied. These results are in qualitative agreement with the analogous dependence of glass transition temperature.