Morphology-Controlled Synthesis of CeO 2 Microstructures and Their Room Temperature Ferromagnetism

Gear-shape CeO2 microstructures have been synthesized via a facile hydrothermal method with Ce(NO3)3⋅6H2O as the cerium source, NH4HCO3 as both the precipitator and the carbon source, and cetyltrimethyl ammonium bromide (CTAB) as the surfactant. X-ray diffraction (XRD) inferred that the synthesized CeO2 microstructures exhibited a fluorite structure. The band gap (Eg) of CeO2 samples is larger than that of bulk. X-ray photoelectron spectroscopy (XPS) showed that there are plenty of Ce3+ ions and oxygen vacancies at the surface of CeO2 samples. All the synthesized CeO2 samples exhibited the room temperature ferromagnetism, and the saturation magnetization increases with the increases of lattice parameter and Eg. The room temperature ferromagnetism mechanism of gear-shape CeO2 is mainly attributed to the influence Ce3+ ions.