Synthesis and characterization of nickel ferrite nanoparticles via planetary ball milling assisted solid-state reaction

An effective synthesis method is reported for magnetic nickel ferrite (NiFe2O4) nanoparticles involving planetary ball milling assisted solid-state reaction process. The precursors obtained by planetary ball milling the mixture of FeSO4· n2O, NiSO4·, 2O, NaOH and dispersant (NaCl) sufficiently at room temperature were calcined under different conditions to obtain pure NiFe2O4 nanoparticles. The as-synthesized samples were characterized by thermogravimetry (TG) and differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) techniques. The results indicate that the calcination temperature for the precursor obtained by planetary ball milling can be lower to 750 °C to obtain impurity-free NiFe2O4 nanoparticles with wide size distribution and double morphology, which is attributed to the higher reactivity of the precursor. The presence of defects and strains, derived from the continual ball collisions with high energy in the planetary ball milling process, is accounted primarily for the characteristics of magnetic properties. The solid-state reaction mechanism was proposed based on the analysis results of XRD, TEM and EDS. The planetary ball milling assisted solid-state reaction technique is considered to be a simple and effective synthesis method for NiFe2O4 and other interesting nanomaterials.