TY - CONF A1 - Kiefer, P. A1 - Balzer, R. A1 - Dietrich, U. A1 - Behrens, H. A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Deubener, J. T1 - Viscosity of water bearing glasses in the glass transition range – Phosphates vs. silicates and borates N2 - Water has a strong impact on the viscosity and the transition temperature of oxide glasses. It acts as a fluxing agent, reducing viscosity particularly in the glass transition range, and by that flattening the viscosity-temperature curve and decreasing the fragility of hydrous glass melts. This general behavior is found for silicate and borate as well as in borosilicate compositions. However, there is still a lack of data with respect to hydrous phosphate glasses. Here, we study the influence of structural water on the viscosity of Li2O-MgO-(Al2O3-)P2O5 glasses. The glasses were synthesized in an internally heated pressure vessel (IHPV) at a pressure of 0.5 GPa. The selected pressure allows for the synthesis of glass specimens with water contents of several wt.%. The viscosity measurements were carried out in the glass transition range, i.e. log η ≈ 10-13 (η in Pa s), using a sphere penetration viscometer. The measured data agree with glass transition temperatures measured by differential thermo analysis. First results further suggest that the fragility of the analyzed phosphates decreases with increasing water content. T2 - 91. Glastechnische Tagung CY - Weimar, Germany DA - 28.05.2017 KW - Water-bearing glasses KW - Viscosity PY - 2017 AN - OPUS4-40812 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -