High Glass Transition Temperature Barium Silicophosphate Glasses Designed with Topological Constraint Theory

Alkali‐free glasses have attracted tremendous attentions for their high glass transition temperature ( T g ). Such a feature broadens their potential applications, especially in the area of high‐density and high‐power laser glasses. BaO–P 2 O 5 glasses, as one of the major matrix materials due to its high‐ T g , can be applied in high‐power laser glasses. Introducing SiO 2 is an effective method to improve the thermal, refractive index, and mechanical properties of phosphate glasses. Herein, we studied the barium silicophosphate glasses with MAS NMR and the T g was successfully calculated by the topological constraint theory. The designed glass (20BaO–26.7SiO 2 –53.3P 2 O 5 , mol%) with a high T g (789K) was prepared and it also exhibited high refractive index and high Vickers hardness, suggesting the barium silicophosphate glasses have widespread applications in high‐power laser glasses and optical fibers.