Combustion Synthesis and Characterization of Nanocrystalline CeO<INF>2</INF>-Based Powders

Nanocrystalline cerium oxide based powders (CeO<INF>2</INF>, (GdO<INF>1.5</INF>)<INF>0.2</INF>(CeO<INF>2</INF>)<INF>0.8</INF>, and (SmO<INF>1.5</INF>)<INF>0.2</INF>(CeO<INF>2</INF>)<INF>0.8</INF>) have been produced using combustion synthesis with glycine as fuel and nitrate as oxidizer. The pure CeO<INF>2</INF> powders prepared by using different glycine-to-nitrate ratios have been characterized by X-ray diffraction (crystallite size), thermogravimetry, infrared spectroscopy, surface area analysis, and transmission electron microscopy. The influence of calcination temperature on crystallite size, surface area, and carbonate species remaining from the combustion reaction has been studied especially for the near stoichiometric glycine/nitrate ratio (G/N = 0.55) to reveal the optimal synthesis conditions for all three compositions. A G/N ratio of 0.55 and calcination at 550 °C in oxygen flow gave high quality powder with a crystallite size of ~10 nm. The powders had excellent sintering properties with an onset of densification at ~600 °C.