The impact of Ta ₂ O ₅ in multinucleating agents on chemically strengthened MgO–Al ₂ O ₃ –SiO ₂ transparent glass‐ceramics

Abstract MgO–Al 2 O 3 –SiO 2 (MAS) glass‐ceramics are significant due to their excellent mechanical properties. However, most of these glass‐ceramics are opaque and lack chemically strengthened capabilities. In this study, chemically strengthened transparent MAS glass‐ceramics were successfully synthesized by employing SnO 2 + ZrO 2 + Ta 2 O 5 as a multinucleating agent. Systematic investigation was conducted using differential scanning calorimetry (DSC), X‐ray diffraction (XRD), transmission electron microscope (TEM), field emission scanning electron microscope (FE‐SEM), Scattered Light Photoelastic Stress Meter (SLP), and Vickers hardness measurements. The results show that Ta 2 O 5 exhibits a good nucleation effect. With the increase of Ta 2 O 5 content from 0 mol% to 0.5 mol%, the exothermic peak temperature of the precipitated crystals decreased from 976.3°C to 937.6°C. The primary crystalline phases precipitated in the MAS system were MgAl₂O₄ (PDF#21‐1152) and ZnAl₂O₄ (PDF#05‐0669), with secondary phases including SnO 2 (PDF#46‐1088), ZrO 2 (PDF#50‐1089), and Ta 2 O 5 (PDF#21‐1198). TEM‐tested interplanar spacing data and electron diffraction ring data further confirmed the presence of these crystalline phases. At 0.5 mol% Ta 2 O 5 content, after crystallization at 920°C, the average grain size was approximately 40.34 nm, with 86.57% transmittance at 550 nm. The Vickers hardness of the parent glass increased from 6.68 GPa to 7.17 GPa after heat treatment at 920°C. Following 5 h of ion exchange, Vickers hardness increased to 7.97 GPa, with surface compressive stress (CS) of 150.29 MPa and depth of layer (DOL zero ) of 80.96 µm. After 24 h of ion exchange, Vickers hardness reached 8.16 GPa, with CS of 239.86 MPa and DOL zero of 93.28 µm. The conclusions provide new insights for further study of the MAS system and broaden its application field such as in cover materials.