Continuous synthesis of carbon-encapsulated magnetic nanoparticles with a minimum production of amorphous carbon

The continuous synthesis of carbon-encapsulated magnetic nanoparticles is described using an inductively coupled radio frequency thermal plasma torch. The synthesis uses the simultaneous vaporization of iron powder and a liquid carbon source in the plasma jet. It was found that the process parameters could be adjusted to minimize the amorphous carbon content in the product. It could be achieved using either aliphatic alcohols (processed in Ar plasma) or hydrocarbons (processed in Ar–O2 plasma). In such circumstances the oxygen etches any amorphous carbon particles produced. Complete reduction of amorphous carbon was achieved when ethanol was used as a carbon feedstock.