Sintering and properties of nanosized ceria solid solutions

The effect of small amounts (<5 mol.%) of cobalt oxide on the sintering characteristics and electrochemical performance of cerium oxide solid solutions have been evaluated. Ce0.8Gd0.2O2−x powder with an average crystallite size of 20 nm served as model substance for electrolytes with a high oxygen ionic conductivity and low electronic conductivity. Sintering to >99% of the theoretical density has been achieved at temperatures below 900°C resulting in an average grain size less than 150 nm in the sintered material. AC and DC conductivity measurements on bulk material revealed that for transition metal oxide doping below 2 mol.% the ionic conductivity remains unchanged compared to pure CGO.