Solid-Phase Synthesis of Carbon-Encapsulated Magnetic Nanoparticles

Abstract

Carbon-encapsulated magnetic nanoparticles (CEMNPs) have wide applications. However, synthesis of such particles with superparamagnetic properties is still a great challenge. The present study reports a new method for the production of CEMNPs in the solid state. An Fe/C solid solution was first prepared by pyrolysis of Fe(CO)5 and C2H2. Heat treatment of this material at low temperatures (≤600 °C) generated fine nanoparticles (∼7 nm) with superparamagnetic properties, but treatment at high temperatures (>600 °C) produced larger nanoparticles (≥30 nm) exhibiting permanent magnetic behavior. The advantages of the present solid-phase approach over previous gas-phase methods include good controllability of particle size and thus magnetic properties and suitability for large-scale production.