Preparation of magnetic cobalt nanoparticles by reducing hydrazine

CoCl_2·6H_2O is reduced to magnetic cobalt nanoparticles by the hydrazine reduction method in the ethanol system.The particles are packed by polyvinylpyrrolidone(PVP) to be protected from oxidation.The structure and the valency state of cobalt nanoparticles are measured by XRD and XPS.The dimension is surveyed by TEM and laser particle sizer detector respectively.The results show that the cobalt nanoparticles consist of both hcp phase and fcc phase,and the average size is about 30nm.The circular grains are dispersed well in hexane.