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

• We study the composition–structure–property relations of calcium aluminate glasses.
• Various additives to improve glass formation are investigated.
• Addition of SiO2: increase in Tg, but decrease in fragility and crack resistance
• Partial substitution of Ca2 + for R2 +: modifier field strength is decisive.

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.