Sol-gel synthesis and properties of Ce1-xGdxO2-x/2 solid solutions

A series of solid electrolytes Ce1-xGdxO2-x/2(x=0 similar to0.6) was prepar ed by sol-gel method. The structure, thermal expansion coefficient and elec trical properties of the solid solutions were systematically studied. XRD d ata showed that a complete cubic fluorite structure was formed at 160 degre esC. The purity of the product prepared by the sol-gel method is higher, th e grain size is uniformly smaller. They were easily sintered into highly de nse ceramic pellets at 1 300 degreesC. The sintering temperature was signif icantly lower than that by traditionally high temperature solid phase react ion method. The thermal expansion coefficient of Ce0.8Gd0.2O1.9, determined from high- temperature XRD data, is 8. 125 X 10(-6) K-1. Impedance spectra analyses showed that the grain-boundary resistance of the solid electrolyt e prepared by sol-gel method was reduced or even eliminated. The conductivi ty of Ce0.8Gd0.2O1.9 is 5.26 X 10(-3) S/cm at 600 degreesC. The activation energy (E-a) is 0.82 eV.