Ceramic oxide electrolytes based on CeO2—Preparation, properties and possibility of application to electrochemical devices

Samples of pure CeO2, Ce1−xSmxO2, Ce1−x(Sm0.5Ca0.5)xO2, where 0 < x < 0.25 or Ce0.2−xSmxYxO2, within 0 < x < 0.2 were sintered from fine powders obtained by the citrate method. The preparation method, microstructure, and structure of samples are presented and discussed. All powders and sinters were found to be ceria-based solid solutions of the fluorite type structure. The results of hardness, fracture toughness measurements are reported. The results of electrical properties of the samples investigated by an ac impedance spectroscopy in temperature range 150–700 °C and for frequency range 10−2 to 107 Hz are also presented and discussed. The electrical properties of ceria co-doped with Sm2O3 and Y2O3 or CaO and Sm2O3 samples are found to be improved very little compared to only the samaria or yttria-doped ceria. The best oxygen ion conductivity was found for the Ce0.8Sm0.1Y0.1O2 compound. Testing results of this compound used as an electrolyte in oxygen-concentration cell are also reported.