Magnetic properties of nanocrystalline Sm-substituted CoFe2O4 synthesized by citrate precursor method

Addition of Sm3+ ions (where x = 0–0.4) to form CoFe2−xSmxO4 nanocrystalline powders synthesized using citrate precursor method has been studied. Effects of substitution Fe3+ ions by Sm3+ ions and thermally treated temperature (400–1000 °C) on the structure, crystallite size, morphology and magnetic properties of the produced cobalt ferrites nanocrystals were investigated. The produced materials were characterized by X-ray diffraction analysis (XRD) and the results revealed that a single phase of cobalt ferrite CoFe2O4 was formed without Sm addition at different thermally treated temperatures. Addition of Sm formed the broad peaks of cobalt ferrite phase at low temperatures 400–600 °C and it led to the formation of cubic cobalt spinel ferrites and SmFeO3 phases at high temperatures from 800 to 1000 °C. The average crystallite sizes of the produced materials were varied by altering the synthetic conditions and they were within the average range of 8 nm and maximum 86 nm. The magnetic properties of the produced powders have been studied using vibrating sample magnetometer (VSM). Saturation magnetization and coercive field are strongly dependent on the calcination temperature and structure of the formed powders. The saturation magnetization was decreased by increasing the Sm content and increased by increasing the calcination temperatures from 400 to 800 °C.