A magnetic-field-assisted solution-phase route to cobalt thin film composed of cobalt nanosheets

In this paper, we report a one-step solution-phase approach to synthesize hexagonal close-packed (hcp) phase Co thin film composed of Co nanosheets generated by chemical reduction of Co2+-EDTA complexes under an external magnetic field. The as-prepared Co film was characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and superconducting quantum interference device (SQUID) magnetometer. The effects of synthetic conditions, such as solvents, reaction temperature and intensity of the magnetic field, on the morphology of the final products were investigated. The coercivity of the as-prepared Co thin film measured in the directions parallel and perpendicular to the film plane reached 321.7 Oe and 220.5 Oe, respectively, which was much higher than that of the bulk Co counterpart. The facile magnetic-field-assisted solution-phase route presented here may provide a new method to prepare magnetic thin film composed of magnetic nanocrystals with anisotropic shapes.