Y2O3 transparent nanoceramics via SPS and ZrO2-doping

The synergistic effect of spark plasma sintering (SPS) and 0–15 mol. % of ZrO₂ doping on the microstructure, mechanical and optical properties of Y₂O₃ transparent ceramics was investigated. ZrO₂-doped Y₂O₃ were obtained by SPS at 1300–1600 °C. Sintering at 1500 °C leads to defect-free, fully dense material with submicron grain size. The grain size of ceramics decreases from 5.2 to 0.11 µm for Y0Z and Y15Z, respectively, since ZrO₂ acts as a grain growth inhibitor. The optimal concentration of ZrO₂ to achieve the highest transparency of yttria is 3 mol. % (82.5 % for λ=5 μm). Increasing concentration of Zr⁴⁺ ions increases the number of interstitials $O_i^{″}$, leading to a less efficient elimination of porosity. Vickers microhardness increased from 7.06 to 11.17 GPa with an increase in ZrO₂ concentration, while opposite behavior was observed for fracture toughness. The influence of grain size and ZrO₂ concentration on elastic modulus, shear modulus and Poisson’s ratio was not revealed.