Controlled synthesis and magnetic properties of hard magnetic CoxC (x=2, 3) nanocrystals

We report our recent results in synthesis and characterization of cobalt carbide (Co3C and Co2C) nanoparticles and nanowires. The synthesis methods were based on a simple one-pot tetraethylene glycol reduction process. By changing the synthesis parameters, the nanocrystal morphology can be adjusted from nanoparticles with different size to nanowires. The magnetic properties of the nanostructure and their correlation to the crystalline structures and the nanoscale morphology have been investigated theoretically and experimentally. It is revealed that the properties are related to both the crystal structures and the morphology.

Research highlights
► A facile polyol reduction procedure has been developed for preparation of cobalt carbide nanoparticles and nanowires.
► The formation mechanism of the nanoparticles and nanowires has been discussed.
► The crystal structure and their magnetic properties are investigated via both experimental and theoretical studies.
► The highest coercivity of the obtained cobalt nanocrystals is 3.1 kOe at room temperature.
► This polyol reduction may be extended to preparation of nanocrystals of other pure transition metals and their carbides.