Fabrication, microstructure and properties of transparent Yb:Y2O3 ceramics from co-precipitated nanopowders

Ytterbium-doped yttrium oxide (5 at.%Yb:Y2O3) nanopowders were synthesized by the co-precipitation method in this work. The influence of the molar ratio of ammonium hydrogen carbonate to metal ions (NH4HCO3/M3+, defined as R) on the properties of the precursors and powders was studied. The powders calcined at 1100 °C from the precursors with different R showed the same phase as the pure cubic Y2O3. However, the agglomerations of the calcined powders were influenced by the R evidently and the 5 at.%Yb:Y2O3 powders with R = 4.0 showed better dispersivity. Using the obtained powders as starting materials, 5 at.%Yb:Y2O3 transparent ceramics were fabricated by vacuum sintering and hot isostatic pressing (HIP) post-treating. The 5 at.%Yb:Y2O3 ceramics with R = 4.0 possessed the best optical quality with the in-line transmittance of 81.2% at 1100 nm with fine grains. In addition, the microstructures of the 5 at.%Yb:Y2O3 transparent ceramics with different R values were also studied and the HIP post-treated ceramics exhibited homogeneous microstructures. Meanwhile, the absorption and emission cross-sections of the 5 at.%Yb:Y2O3 ceramics were calculated to be 0.99 × 10−20 cm2 at 976 nm and 0.97 × 10−20 cm2 at 1031 nm, respectively. The gain spectra also were obtained from the absorption and emission spectra.