EFFECTIVE VISCOSITY AND GLASS TRANSITION TEMPERATURE OF Cs<sub>2</sub>O–B<sub>2</sub>O<sub>3</sub> MELTS

Abstract

Effective viscosity (viscoelasticity) of cesium and boron oxides melts was measured at temperatures 900–1600 K and concentrations 0 ≤ x ≤16 mol % Cs2O by vibration viscosimetry. It was shown that vibration leads to non-Newtonian flow of melts. This means that not only configuration activation energy, the switching energy of bridging oxygen bonds but also the elastic energy of structural units of melts associated with activation energy of viscous flow. Using parameters under conditions of Newtonian and non-Newtonian flow of melts, shear viscosity η', elastic modulus G' and stored viscosity η'' were calculated. It was shown that cesium boron melts in conditions of high shear rates can be considered as liquids with viscous and elastic properties. Glass transition temperature (Tg, K) was measured by DSC, its dependence of content of cesium oxide was plotted and explained.