Highly Transparent Mg 0.27 Al 2.58 O 3.73 N 0.27 Ceramic Prepared by Pressureless Sintering

A novel aluminum magnesium oxynitride transparent ceramic with the chemical formula Mg 0.27 Al 2.58 O 3.73 N 0.27 was firstly prepared by pressureless sintering of fine single‐phase powders at 1875°C for 24 h in nitrogen atmosphere. The ceramic was fully dense with the average grain size of 57.5 μm. The sample showed excellent in‐line transmission from the visible to middle‐infrared wavelengths with the maximum transmittance of 84%, which could be attributed to rare pores in the sintering body. The material also exhibited good mechanical properties of Vickers hardness (13.39 ± 0.18 GPa), fracture toughness (2.46 ± 0.3 MPa/m 1/2 ), and flexural strength (274 ± 6 MPa).