The synthesis of carbon coated Fe, Co and Ni nanoparticles and an examination of their magnetic properties

Carbon coated Fe, Co and Ni nanoparticles (Fe@C, Co@C, and Ni@C, respectively) have been produced by high pressure chemical vapour deposition. Scanning electron microscopy images prove that carbon coated particles with a Fe, Co, and Ni core are formed. High-resolution transmission electron microscopy images show that the nanoparticles have a size distribution from 2 to 100 nanometers and display the core/shell structure with one or more particles forming the core in a particular shell. From X-ray diffraction peaks the phase of the core material is confirmed and the average particle size is determined from the width of the peaks to be 16, 21, and 19 nm for Fe@C, Co@C, and Ni@C, respectively. The coated nanoparticles are ferromagnetic at least up to 400 K. AC magnetic heating studies have been performed which imply their potential for applications in hyperthermia therapy.