Properties of Nitrogen‐Containing Yttria—Alumina—Silica Melts and Glasses

Abstract

The viscosity and solubility of nitrogen in Y 2 O 3 –Al 2 O 3 –SiO 2 melts have been systematically examined. The effects of nitrogen content on viscosity for Y‐Al‐Si‐O‐N melts and on Vickers hardness of oxynitride glasses also have been examined. Although the viscosity of Y 2 O 3 –Al 2 O 3 –SiO 2 melts was decreased, the solubility of nitrogen into the melts was increased with increased Y 2 O 3 content. These results indicated that the yttrium ion behaved as a network modifier. Therefore, the structural units for viscous flow became small, and the amount of nonbridging oxygen increased in the melts when the Y 2 O 3 content increased. The viscosity of Y‐Al‐Si‐O‐N melts and Vickers hardness of oxynitride glasses remarkably increased with increased nitrogen content. These results suggested that the substitution of nitrogen for oxygen in the melts may have led to a high average coordination of nonmetal atoms and that the increased cross‐linking produced a more rigid glass network.