Synthesis and Magnetic Characterization of Graphite-Coated Iron Nanoparticles

Figure 4

Assumed development of GFeNps: At 800°C, smaller magnetite nanoparticles coalesce into a larger polycrystalline one under Ar atmosphere. At 900°C, hydrogen reacts with methane to produce carbon and carbon-hydrogen derived species, which impinge on the partially melted iron surface to form a thin carbon-rich iron surface. After reaching the carbon supersaturation, graphene nucleates at the grain boundaries and then it conformally grows to completely coat the particle surface.