Synthesis and magnetic properties of CoFe2O4 ferrite nanoparticles

CoFe2O4 ferrite nanoparticles were prepared by a modified chemical coprecipitation route. Structural and magnetic properties were systematically investigated. X-ray diffraction results showed that the sample was in single phase with the space group Fd3m-Oh7. The results of field-emission scanning electronic microscopy showed that the grains appeared spherical with diameters ranging from 20 to 30 nm. The composition determined by energy-dispersive spectroscopy was stoichiometry of CoFe2O4. The Curie temperature in the process of increasing temperature was slightly higher than that in the process of decreasing temperature. This can be understood by the fact that heating changed Co2+ ion redistribution in tetrahedral and in octahedral sites. The coercivity of the synthesized CoFe2O4 samples was lower than the theoretical values, which could be explained by the mono-domain structure and a transformation from ferrimagnetic to superparamagnetic state.