Shape-controlled synthesis and their magnetic properties of hexapod-like, flake-like and chain-like carbon-encapsulated Fe3O4 core/shell composites

A shape-controlled synthesis of carbon-encapsulated Fe3O4 core/shell (Fe3O4@C) composites is reported in this paper. By tuning the reaction temperature from 500 °C to 700 °C and the amount of ammonium acid carbonate (1.0 g, 0.5 g and 2.0 g) in a sealed reaction system, Fe3O4@C composites with hexapod-like, flake-like, and chain-like morphologies have been successfully obtained using ferrocene as the precursor. Corresponding hollow carbon structures can be obtained by acid treatments. The three kinds of Fe3O4@C composites show ferromagnetic properties at room temperature, while their saturation magnetizations and coercivities are obviously different from each other, due to the various shapes and structures. Possible formation processes of these Fe3O4@C composites and corresponding hollow carbon materials are discussed. The experimental results indicate that the reaction temperature and the amount of ammonium acid carbonate play key roles in the shape-controlled synthesis of hexapod-like, flake-like and chain-like Fe3O4@C composites.