Optimizing liquid phase promotion effect by modifying powder specific surface area in Si4+/Mg2+ co-doped transparent Yb:YAG ceramics

Utilizing the Si4+/Mg2+ co-doping has been considered an effective approach to fabricate highly transparent ceramics. However, the optimum doping concentration has been reported with considerable uncertainties. In this work, highly transparent Yb:YAG ceramics were obtained via the solid-state method and the sintering behavior is discovered to be closely related to both the doping concentration of Si4+/Mg2+ and the specific surface area (SBET) of powders. SBET is effectively modified by setting the ball-milling time, where the maximum SBET (30.914 m2/g) is achieved with 24 h ball-milling time. With increasing SBET, less Mg2+ is required for better optical properties. When SBET equals 30.914 m2/g, the highest in line transmittance @ 1100 nm of 84.85% is obtained with Si4+/Mg2+ doping concentrations of 0.50 wt% and 0.05 wt%, respectively. The relation between SBET and optimum doping concentration is explained by the different magnitudes of liquid phase promotion required for different contact areas between powder particles.