Sintering and electrical properties of Ce0.8Y0.2O1.9 powders prepared by citric acid-nitrate low-temperature combustion process

Ce0.8Y0.2O1.9 nanopowders were prepared using a citric acid-nitrate low-temperature combustion process. The effect of pH value of the solutions on the ionization of citric acid and the chelating of metal ions was studied. It was found that when the pH value of the solutions was bigger than 6, the citric acid was completely ionized and the stable complexes were formed between rare earth metal ions and the citric acid. Then the stable gels were obtained. The effect of the amount of oxidants (Φ) on the combustion fashions and combustion reaction time of the gels, the properties of the as-synthesized powders, the sintering behavior of the as-synthesized powders and the conductivity of the sintered pellets was also investigated. The results showed that the green density, sintered density and the ionic conductivity of the specimens increased with Φ. When Φ was equal to 1.5, the powders with good dispersion and compressibility were obtained, and the green density of the powders was 52.5%. The relative density of the sintered sample was over 95% at 1350 °C for 4 h and the conductivity of the sintered specimen was 0.034 S cm−1 at 700 °C.