Structure-property relations in calcium aluminate glasses containing different divalent cations and SiO₂

Calcium aluminate glasses are transparent in the infrared region, exhibit ultralow optical losses, and possess excellent mechanical properties. However, these systems exhibit poor glass-forming ability, and it is therefore important to understand their composition-structure-property relations to enable the design of new compositions with optimized properties and glass-forming ability. In this paper, we study the structure-property relationships in CaO-Al₂O₃ based glasses with different additives (SiO₂, MgO, SrO, BaO, and ZnO). Our results reveal a gradual change in all the measured properties (molar volume, hardness, crack resistance, glass transition temperature, and liquid fragility) upon the addition of SiO₂ to the eutectic 64CaO-36Al₂O₃ composition and the partial substitution of CaO for different divalent cation oxides. The relation between the measured liquid fragility index and the glass-forming ability is also investigated. We discuss these phenomena based on structural information obtained by Raman spectroscopy and topological considerations.