Ionic conductivity and mechanical properties of Y2O3-doped CeO2 ceramics synthesis by microwave-induced combustion

We developed a new method, i.e. microwave-induced combustion synthesis to produce highly sinterable Y2O3-doped CeO2 nanopowders. The process took only 15 min to yield Y2O3-doped CeO2 powders. We also investigated the conductivity of Y2O3-doped CeO2 ceramics. It was found Y2O3 concentration to have a large effect on the morphology, activation energy, ionic conductivity, and mechanical properties of Y2O3-doped CeO2 ceramics. The results revealed that the bulk densities of Y2O3-doped CeO2 ceramics sintered at 1420 °C for 5 h were all higher than 92% of the theoretical densities, and the maximum ionic conductivity, σ800 °C = 0.023 S/cm at 800 °C, the minimum activation energy, Ea = 0.954 eV determined in the temperature of 300–800 °C and the maximum fracture toughness, KIC = 1.825 ± 0.188 MPa m1/2 were found for 9 mol.% Y2O3-doped CeO2 specimen. The grain size of CeO2 decreases with increasing Y2O3 concentration. The fracture toughness was found to increase at increased Y2O3 concentration, because of the decrease of CeO2 grain size.