Preparation of nanocrystalline CO1-xNixFe2O4 ferrite and effect of Ni2+ on its magnetic properties

Nanocrystalline Co1-xNixFe2O4 ferrite powder with 0 &le x &le 1 was prepared by the spraying-coprecipitation method. The microstructure of Co1-xNixFe2O4 ferrite powder was characterized by thermogravimetry-differential scanning calorimetry, X-ray diffraction (XRD), transmission electron microscope and specific surface area test. The magnetic properties of Co1-xNixFe2O4 ferrite were measured with a vibrating sample magnetometer at room temperature. The results show that uniform and fine nanocrystalline Co1-xNixFe2O4 ferrite powders are obtained by the spraying-coprecipitation method. Nanocrystalline Co1-xNixFe2O4 ferrite has a solid solution of the spinel structure according to the XRD patterns. The grain size of powder calcined at 600°C for 1.5 h is about 40 nm. There are few agglomerates with average sizes below 100 nm. The specific saturation magnetization and coercivity of nanocrystalline Co1-xNixFe2O4 ferrite decrease with the increase of the content of Ni2+ at room temperature.