Fast pressureless sintering of highly transparent AlON ceramics with broad optical transmission range

Abstract In our recent work, AlON ceramics with transmittance ≥80% at 380–4150 nm were fabricated via pressureless sintering at 1880°C for 2.5 h by reducing Y enrichment. To further improve transparency and gain a deeper insight into the fast densification behavior, a new nano‐sized Y2O3 powder prepared via the Pechini method (NGY‐P), together with the Y2O3 powders used in the previous work, was employed to investigate the effects of Y distribution on densification process and transparency of AlON ceramics. In the entire densification process, diffusion through liquid phase at the grain boundaries dominates the mass transport mechanism when the nano‐sized Y2O3 is doped. Moreover, by optimizing the Y distribution, rapid high densification sintering is achieved, and grain growth is effectively suppressed. As a result, highly transparent AlON ceramics were successfully fabricated by doping with NGY‐P, achieving transmittance of ≥80% across the 350–4480 nm wavelength range after dwelling for 4.0 h, with the maximum transmittance of 87.2% and Vickers hardness of 17.05 ± 0.36 GPa.