Effect of ZnO, SiO2 dual shells on CeO2 hybrid core-shell nanostructures and their structural, optical and magnetic properties

摘要

This work has investigated the structural, optical and magnetic properties of ceria-based core-shell nanostructures synthesized by a simple and effective precipitation method. Formation of the core CeO2 and shells of ZnO as well as SiO2 over the core is confirmed by the X-ray diffraction (XRD) pattern, Fourier transform infra-red spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). The optical properties of the core-shell nanostructures are determined by UV-visible spectroscopy and photoluminescence (PL) studies. From XRD results it can be seen that the core CeO2 exhibits cubic fluorite and hexagonal ZnO shell structures. A core-shell nanostructure with complete coating of SiO2 on CeO2@ZnO is evidenced by FTIR. UV-visible spectra show broad absorption maxima in the UV region and also show a shift in the band edge for core-shell nanostructures which demonstrate the electronic structural modification in the core-shell nanoparticles. Magnetic studies show room temperature ferromagnetic order in the low field region with significant coercivity, which may be associated with defect-related ferromagnetic exchange in the core-shell nanostructures.