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.