Preparation and magnetic properties of carbon encapsulated iron nanocapsules from starch

Carbon encapsulated iron(Fe@C) nanocapsules were successfully prepared by pyrolyzing iron/starch composites under mild conditions,in which starch functioned as carbon precursor and stabilizer for iron nanoparticles.The as-obtained Fe@C nanocapsules were examined by TEM,XRD and a vibrating sample magnetometer.Results show that the Fe@C nanocapsules with diameters in a narrow range of 30-40 nm feature well-constructed core/shell structures,consisting of a bcc-Fe core and a graphitic shell.The Fe@C nanocapsules have a low ratio of remanence to saturation magnetization(M_r/M_s = 0.11),implying that they are superparamagnetic at room temperature.