Iron, cobalt and nickel nanoparticles encapsulated in carbon obtained by the arc evaporation of graphite with the metals

Arc evaporation of graphite with Fe, Co and Ni yields two distinct types of metal nanoparticles, wrapped in graphitic layers and highly resistant to oxidation. Electron microscopy shows that the metal particles (10–40 nm) in the stub region are encap- sulated in carbon onions, the particles in the soot being considerably smaller (2–15 nm). The metal particles in the soot are either ferromagnetic with lowered Curie temperatures or superparamagnetic.