Carbon-encapsulated Magnetic Nanoparticles Research Articles

Synthesis of carbon-encapsulated magnetic nanoparticles by a grain-boundary-reaction

AbstractCarbon-encapsulated ferric magnetic nanoparticles were prepared by the grain-boundary-reaction of ultrafine goethite particles. The mechanism of the grain-boundary-reaction was studied with high-resolution transmission electronic microscope, X-ray diffraction and thermo gravimetric analysis. The magnetic properties are measured with a vibrating sample magnetometer. The diameter of carbon-encapsulated ferric magnetic nanoparticles is 30~60 nm, and the coercive force and saturate magnetization are 315 Oe and 30 emu /(g powder), respectively. These composite particles are very stable in air.

Large-scale preparation of carbon-encapsulated cobalt nanoparticles by the catalytic method

With strategical selection of the water-soluble sodium chloride (NaCl) as the supporting material, we realized large-scale production of carbon-encapsulated cobalt nanoparticles with a productivity of almost 100%. The products can be fully separated from the supporting materials by simple washing process. When NaCl, NaF and Al 2O 3 were used as supporting materials, the morphologies of the carbon products changed from carbon-encapsulated magnetic nanoparticles (CEMNs) to an intermediate state (quasi-nanocages) between CEMNs and carbon nanotubes (CNTs), and then to CNTs, respectively. NaCl shows strong inhibiting effects on the growth of CNTs, favoring the formation of CEMNs.