Facile hydrothermal synthesis of large-scale monodisperse 3D flower-like CeO₂ nanospheres and their excellent magnetic properties

Abstract

The monodisperse 3D flower-like CeO₂ nanospheres with many channels have been purposefully synthesized via controlling the morphology of corresponding CeCO₃OH precursors by a facile hydrothermal method. The X-ray diffraction results indicate that the calcined samples have a cubic fluorite structure of CeO₂ with no crystalline impurity phase. The scanning electron microscope and transmission electron microscope images display that the flower-like nanospheres with a diameter of 200–400 nm are composed of numerous irregular nano-particles as the petals with less than 100 nm in diameter, which are found highly oriented and perpendicularly aligned with lower density to form an open porous structure. X-ray photoelectron spectroscopy and Raman analyses demonstrate that a certain amount of Ce³⁺ ions and oxygen vacancies exist in the surface of CeO₂ samples. The magnetic measurements show that the obtained samples have excellent ferromagnetism at room temperature, which can be reasonably explained for the influences of the morphology of samples, oxygen vacancies and Ce³⁺ ions.