Hydrothermal synthesis of hexagonal CeO2 nanosheets and their room temperature ferromagnetism

Hexagonal CeO2 nanosheets of 40–50 nm in thickness and 300–400 nm in side-length have been successfully synthesized via controlling the morphology of CeCO3OH precursors by a facile hydrothermal technique using CeCl3·7H2O as cerium source, ammonium hydrogen carbonate as precipitants, and ethylenediamine as complexant. The reaction time and the amount of CeCl3·7H2O and ethylenediamine were systematically investigated. The as-synthesized hexagonal CeO2 nanosheets were examined by XRD, SEM, TEM, XPS, Raman scattering and magnetization measurements. It is found that the amount of CeCl3·7H2O and ethylenediamine are key parameters for controlling the final morphology. The hexagonal CeO2 nanosheets have a fluorite cubic structure and there are Ce3+ ions and oxygen vacancies in surface of samples. The synthesized CeO2 shows excellent room temperature optical properties. M–H curve exhibits excellent room-temperature ferromagnetism (RTFM) with saturation magnetization (Ms) of 3.02 × 10−2 emu/g, residual magnetization (Mr) of 0.68 × 10−2 emu/g and coercivity (Hc) of 210 Oe, which is likely attributed to the effects of the Ce3+ ions and oxygen vacancies.