Formation, characterization and magnetic properties of carbon-encapsulated iron carbide nanoparticles

Fe3C nanoparticles encapsulated in carbon shell with a size range of 20–50 nm were obtained in large scale by reacting anhydrous FeCl3, hexamethylenetetramine and metal Na in an autoclave at 650 °C. Magnetization measurements show that the as-obtained materials display superparamagnetic properties at room temperature. A possible formation mechanism of the core–shell nano-structures was discussed.