Preparation of nanocrystalline ceria in CCl4

Nanocrystalline ceria was prepared by a hydrothermal technique using CCl4 as the solvent at 130 °C. X-ray diffraction (XRD) analysis confirmed the cubic phase of ceria with fluorite structure. Transmission electron microscopy analysis showed spherical particles having a narrow size distribution. X-ray photoelectron spectroscopy (XPS) analysis indicated no detectable absorbed Cl− or NO3− ion, demonstrating that CCl4 acting as medium instead of water would introduce no extra impurity ions. Photoacoustic (PA) spectroscopy analysis showed that the PA absorption band shifted blue as well as broadeded accompanying with a blue shift of the absorption edge with the decrease of the grain sizes and this phenomenon was explained by the quantum size effect.