Preparation and characterization of dense Ce0.85Y0.15O2−δ ceramics

The precursor powder of Ce0.85Y0.15O2−δ has been prepared via oxalate coprecipitation from high purity reagents of Ce(NO3)3·6H2O and Y(NO3)3·6H2O. The sinterability, densification and microstructural development have been examined. At all the sintering temperatures used from 1000 to 1550 °C, no intragranular pores are observed. All the pores are located at the grain boundaries or at the triple points. The sample sintered at 1300 °C for 3 h has over 98.0% relative density, and a mean grain size of ∼1.55 μm. Nearly all the pores are eliminated from the sintered bodies, when the sintering temperature is higher than 1300 °C. Higher ionic conductivity [e.g., 4.59 (Ωm)−1 at 750 °C in air] is obtained for the Ce0.85Y0.15O2−δ ceramic sintered at 1300 °C in 3 h. This sample has a fracture toughness of 1.49±0.2 MPa m1/2. However, no fracture toughness dependence of grain size is found for dense Ce0.85Y0.15O2−δ ceramics.