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

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 lm. 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).

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