Viscosity and thermal expansion of soda-lime-silica glass doped with Gd2O3 and Y2O3

In order to reveal the effects of rare earth elements on the rheological behavior of silicate melt, the properties of viscosity and thermal expansion of soda-lime-silica glass doped with Gd2O3 and Y2O3 were investigated by the rotating crucible viscometer and dilatometry. The results show that, introduction of Gd2O3 and Y2O3 increases the coefficient of thermal expansion and decreases viscosity of soda-lime-silica glass. When the amount of Gd2O3 and Y2O3 increases from 0 to 1.00 mol%, the coefficient of thermal expansion of soda-lime-silica glass increases firstly from 7.67 to 7.79 and 8.05, and then decreases to 7.78 and 7.66 ( x 10 -6 C-1) respectively. In the case of melting temperature, its value decreases from 1830K to 1714 K, and then elevates to 1727 K as the content of Gd2O3 up to 1.00 mol%, however, as Y2O3 content increases from 0 to 1.00 mol% the melting temperature decreases monotonously from 1830K to 1737 K. The viscosity, melting temperature and coefficient of thermal expansion of soda-lime-silica glasses codoped with Gd2O3 and Y2O3 are larger, comparing with glasses doped solely with Gd2O3 or Y2O3. The effect of co-doping with Gd2O3 and Y2O3 on thermal expansion and viscosity properties of soda-limesilica glass, which is similar with the mixed-alkali effect in silicate glasses, is also observed.