Effect of agglomeration state of starting powder on fabrication of Tm,Ho co-doped LuAG transparent ceramics

The thulium and holmium co-doped lutetium aluminum garnet (Tm,Ho:LuAG) ceramics were fabricated by vacuum sintering at 1760 °C for 10 h. The raw powders free of sintering aids were synthesized by co-precipitation method. The phase composition, crystalline behaviors, and morphology of the powders calcined at different temperatures were studied by scanning and transmission electron microscopy . Well-dispersed Tm,Ho:LuAG powders with the primary particle size of 80 nm were obtained by calcinations at 1200 °C for 2 h in the muffle furnace. The influence of agglomeration state of starting powder on densification and microstructure of Tm,Ho:LuAG ceramic was explored. The in-line transmittance of Tm,Ho:LuAG ceramic with the thickness of 1 mm reached 83.0% and the corresponding optical attenuation coefficient was about 0.013 mm −1  at 2500 nm. The average grain size of the Tm,Ho:LuAG ceramic was about 1.7 μm. It is promising that the Tm,Ho:LuAG optical ceramic would be a suitable candidate to realize lasers output at 2.1 μm.