Synthesis of cobalt nanoparticles by a modified polyol process using cobalt hydrazine complex

A simple and fast synthetic route is proposed to synthesize spherical, monodispersed, ferromagnetic cobalt nanoparticles by a modified polyol process with an average particle size ranging between 35 and 200 nm. In this process a hydrazine complex of cobalt was employed as a cobalt source. The particle size could be controlled by varying the concentration of polyvinyl pyrrolidone. The shape, structure and magnetic properties of the final products were investigated using X-ray diffraction, small angle X-ray scattering, transmission electron microscopy and vibrating sample magnetometer. The various microstructural parameters of powders such as crystallite size, strain and volume fraction of hexagonal close packed (hcp) and face centered cubic (fcc) Co phases and also particle size, shape and their distribution have been determined. The magnetic hysteresis loop showed that the coercive force H c and saturation magnetization M s to be 109 Oe and 101 emu/g, respectively for a particle diameter of 35 nm.