Enhancement of magnetic properties in hard/soft CoFe2O4/Fe3O4 nanocomposites
CoFe2O4/Fe3O4 nanocomposites with different concentrations of soft ferrite (Fe3O4) were fabricated using a co-precipitation method. Crystal structure, phase composition, morphology and magnetic properties of as-synthesized nanocomposites were characterized by X-ray diffraction (XRD), inductively coupled plasma (ICP), Mössbauer spectroscopy (MS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). Results from XRD and MS reveal that the nanocomposites are composed of two phases (CoFe2O4 and Fe3O4), both of which have a spinel structure. SEM and TEM show that the average particle size of the nanocomposites is about 20 nm. VSM indicates that all hysteresis loops exhibit a single-phase-like behaviour. The remanence ratio (Mr/Ms), coercivity (Hc) and maximum magnetic energy product (BH)max are significantly enhanced in all the nanocomposites compared with pure hard ferrite (CoFe2O4). The enhancement of the magnetic properties may be attributed to the exchange coupling interaction in the system.