Solvothermal synthesis and characterization of NiFe2O4 nanospheres with adjustable sizes

NiFe2O4 nanospheres with adjustable sizes have been successfully synthesized via a facile solvothermal method. The average sizes of NiFe2O4 nanospheres could be controlled from 7 to 200 nm by changing experimental parameters such as the amount of NaOH and reaction duration. The structure, morphology, sizes and magnetic properties of final products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The sizes of NiFe2O4 nanospheres sensitively depended on the amount of NaOH. The saturation magnetization ( M s ), remanent magnetization ( M r ), and coercivity ( H c ) increased as the average sizes of NiFe2O4 nanospheres increased.