Fabrication of Yb:Sc2O3 transparent ceramics from co-precipitated nanopowders: The effect of ammonium hydrogen carbonate to metal ions molar ratio

5 at%Yb:Sc2O3 transparent ceramics were fabricated by the co-precipitation and vacuum sintering method. NH4HCO3 and (NH4)2SO4 were used as precipitant and dispersing agent in the precipitation process, respectively. The influence of ammonium hydrogen carbonate to metal ions molar ratio (R value) on the morphology, agglomeration of resultant powders and the optical quality of transparent ceramics was investigated systematically. It was found that all the calcined powders synthesized with different R values exhibited same phase. The morphology of the precursors and calcined powders was investigated by FESEM, and the results show that the R value has a significant influence on the morphology of 5 at%Yb:Sc2O3 precursors and calcined powders. The precursors and resultant powders exhibit a severe agglomeration with R = 4.4 and 4.8. Using these powders as starting materials, 5 at%Yb:Sc2O3 transparent ceramics were successfully fabricated by vacuum sintering at 1850 °C for 10 h. There is only little difference in optical transmittances of 5 at%Yb:Sc2O3 ceramics with R value within the 3.2-4.0 range. The ceramic sample with R = 4.0 possesses the best optical quality with the in-line transmittance of 71.9% at the wavelength of 1100 nm. The microstructures of the 5 at%Yb:Sc2O3 transparent ceramics with different R values were also investigated.