Cobalt microtrees assembled by dendrites: Hydrothermal synthesis and their enhanced magnetic properties

Cobalt microtrees assembled by many dendrites were hydrothermally synthesized at 160 °C using hydrazine as the reducing agent. No surfactant or complex reagent was employed for the growth assistance. The structure and morphologies of the obtained products were investigated by XRD, SEM, and TEM techniques. It was found that temperature and concentration of sodium hydroxide played important roles for the formation of cobalt with such novel shapes. The growth mechanism was tentatively discussed on the basis of controlled experiments. Magnetization measurement revealed that the cobalt microtrees exhibited ferromagnetic characteristics with a saturation magnetization of 146.7 emu/g and an enhanced coercivity of 259.0 Oe at room temperature. These cobalt microtrees may have potential applications in magnetic devices.

Graphical abstractCobalt microtrees assembled by many dendrites were hydrothermally synthesized at 160 °C without using any surfactant or complex reagent, and these cobalt microtrees exhibited ferromagnetic characteristics with a saturation magnetization of 146.7 emu/g and an enhanced coercivity of 259.0 Oe at room temperature.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Cobalt microtrees assembled by many dendrites were hydrothermally synthesized at 160 °C. ► No surfactant or complex reagent was employed for the growth assistance. ► Temperature and concentration of sodium hydroxide played important roles for the formation of cobalt microtrees. ► Such cobalt microtrees possessed a saturation magnetization of 146.7 emu/g and an enhanced coercivity of 259.0 Oe at room temperature.