Densification and microstructure evolution of Cr4+,Nd3+:YAG transparent ceramics for self-Q-switched laser

Transparent 0.1 at.% Cr, 1.0 at.% Nd:YAG ceramics were fabricated by solid-state reaction and vacuum sintering using commercial Y2O3, α-Al2O3, Cr2O3 and Nd2O3 as raw materials. CaO and tetraethoxysilane (TEOS) were used as charge compensator and sintering aid, respectively. The powders were mixed in ethanol and doped with TEOS, dried and pressed. Pressed samples were sintered from 1450 to 1800 °C for 10 h. The relative density increased from 68.8% to 99.4% at the sintering temperature from 1450 to 1700 °C. Grain size increased with increase of sintering temperature and obvious grain growth occurred between 1650 and1700 °C. For the Cr,Nd:YAG ceramics sintered at 1750 and 1800 °C for 10 h, nearly pore-free microstructures with average particle size of ∼10 μm were obtained. The optical transmittance of the 1800 °C sintered sample was ∼70% in the infrared wavelength.