Preparation of Transparent MgAlON Ceramics with Tunable Compositions

MgAlON ceramics with excellent optical properties were synthesized using high-purity AlON and commercially available MgO powder. The effect of MgO amount on ceramic sintering was examined in terms of microstructural evolution and grain growth. Furthermore, the process of MgAlON phase formation through the reaction between AlON and MgO was studied. The results revealed that the addition of MgO significantly hindered the formation of α-Al2O3 and AlN phases at temperatures ranging from 1350 °C to 1600 °C, thereby facilitating the stabilization of the spinel-type phase. The optical transmittance and Vickers hardness of MgAlON were investigated through pressureless sintering followed by hot isostatic pressing (HIP). The resulting ceramics, with a MgO mass ratio of 10.0 wt%, exhibited an excellent in-line transmittance of ∼ 82.9% at 0.6 μm and 87.7% at 3.7 μm, and a remarkable Vickers hardness of approximately 13.65 ± 0.21 GPa.