Preparation and characterization of hcp Co-coated Fe nanoparticles

A relatively simple method was described for coating and modifying iron nanoparticles with a hexagonal close-packed (hcp) cobalt layer. It was realized by depositing cobalt onto the poly(N-vinyl-2-pyrrolidone) (PVP) modified iron particles in ethanol solution. XRD, XPS and HRTEM were used to characterize the product. The Co layers, grown as the exclusive hcp phase, were ascribed to the inducement of the body-centered cubic (bcc) iron cores. Thus-prepared hcp Co-coated Fe particles displayed a much enhanced coercivity and decreased saturation magnetization (MS) compared with that of the uncoated sample.