Chemical reduction of nanocrystalline CeO2

The reduction of commercial and mechanochemically processed CeO2 powders was studied. Nanostructured CeO2, with the crystallite size of 21 nm and the lattice distortion of 0.37%, was obtained during 60 min of milling in a high-energetic vibratory mill. X-ray diffraction, scanning electron microscopy and Brunauer-Emmett-Teller method were applied to characterize the milled powders. During the thermal treatment at 1200 and 1400 °C in an argon atmosphere the nonstoichiometric CeO2−x oxides with the defect fluorite structure were formed. Compositions of CeO2−x oxides were determined according to its lattice parameter. The results showed that the release of oxygen, as well as the rate of reduction, was more effective in nanocrystalline then in the microcrystalline CeO2, producing at 1200 °C CeO1.80 and CeO1.85 oxides, while at 1400 °C were obtained similarly, CeO1.77 and CeO1.78, compositions.