Viscosity of nitrogen containing Y2O3-Al2O3-SiO2 melts and hardness of glasses

The viscosity and the solubility of nitrogen for Y2O3-Al2O3-SiO2 melts have been examined systematically. The effects of nitrogen content on viscosity for Y-Al-Si-O-N, and on Vicker's hardness of the oxynitride glasses have been examined. Though the Viscosity Of Y2O3-Al2O3-SiO2 melts was decreased, and the solubility of nitrogen into the melts was increased with increasing the content Of Y2O3 for constant SiO2/Al2O3 ratio, and with increasing the content of Al2O3. These results indicate that Y2O3 and also Al2O3 behave as a network modifier. Therefore, the structural units for viscous flow become smaller, and the amount of non-bridging oxygen increases in the melts as Y2O3 or Al2O3 content increase. The viscosity of Y-Al-Si-O-N glass melts and Vicker's hardness of oxynitride glasses increased with increasing the content of nitrogen. These results suggest that the substitution of nitrogen for oxygen may lead to larger structural units for viscous flow, and that the increase of cross-linking produces a more rigid glass network.