Preparation and characterization of dense Ce_0.85Y_0.15O_2-δ ceramics

The precursor powder of Ce_0.85Y_0.15 O_2-δ has been prepared via oxalate coprecipitation high 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 Ce_0.85Y_0.15 O_2-δ ceramic sintered at 1300 °C in 3 h. This sample has a fracture toughness of 1.49±0.2 MPa m^1/2. However, no fracture toughness dependence of grain size is found for dense Ce_0.85Y_0.15O_2-δ ceramics.