Highly transparent AlON sintered from powder synthesized by direct nitridation

Abstract Transparent AlON ceramic was pressurelessly sintered from powder synthesized by direct nitridation of Al–Al 2 O 3 starting mixtures. TG, SEM and XRD analyses were conducted to investigate the detail procedure of direct nitridation. The Al spheres were dispersed by submicron Al 2 O 3 , then nitrided and reacted with Al 2 O 3 to form AlON. The particle size of AlON is about 10–30 μm with irregular morphology. With the aid of ball milling and sintering additives, 2 mm thick AlON ceramic with in-line transmittance of 80.6% at 1100 nm and above 77.1% at 400 nm was obtained successfully, demonstrating that the direct nitridation method is another promising approach for the preparation of AlON ceramics with high transparency.