Solvothermal synthesis and characterization of cobalt microcrystals with hierarchical radial structure

Three-dimensional (3D) hierarchical cobalt microcrystals composed of well-aligned dendrites radiating from the shaft axis were prepared using cobalt chloride hexahydrate as starting materials via a facile hydrothermal route. The structures and morphologies of products were investigated by X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) measurements. It was found that the dosages of ethylenediamine, sodium hydrate played an important role in the morphology control of the final products. A unique growth mechanism for the radial cobalt microcrystal was tentatively discussed, which offers a fresh and possible solution to the design and fabrication of materials with hierarchical structure. Additionally, Magnetization measurements revealed that the products exhibited ferromagnetic characteristics with a saturation magnetization of 151.7 emu/g and a coercivity of 355.8 Oe at room temperature. The result shows a potential application in ferrofluids and other related magnetic application.

► Hierarchical cobalt microcrystals composed of dendrites were prepared hydrothermally. ► The dosages of ethylenediamine, sodium hydrate play an important role in the morphology control of the products. ► A unique growth mechanism for the radial cobalt microcrystal was discussed. ► The saturation magnetization and coercivity of the products are 151.7 emu/g and 355.8 Oe at room temperature, respectively.