Synthesis of Monodispersed Co(Fe)/Carbon Nanocomposite Microspheres with Very High Saturation Magnetization

Through the complexation of cyano groups in polyacrylonitrile (PAN) microspheres with cobalt (iron) ions under mild conditions, cobalt (iron)-containing PAN microspheres could be prepared effectively, then after pyrolyzation of the composite microspheres at 800 °C under N 2 atmosphere, Co(Fe)/carbon nanocomposite microspheres could be prepared, and the metal content is up to ∼71 wt % in the Co(Fe)/carbon nanocomposite microspheres. Thermogravimetric analysis, transmission electron microscopy, and vibrating sample magnetometry investigation proved that almost all the cobalt nanoparticles were embedded in the interior of the carbon microspheres, which protected the metal nanocrystals (Co or Fe) from oxidation. The microspheres possess high magnetization (Ms is up to ∼161 emu/g) and show near-zero remanence and coercivity (Hc is down to ∼0.012 KOe) at room temperature, suggesting that they are outstanding soft ferromagnets with high magnetic susceptibilities and practically nil hysteresis loss.