Enhancement of magnetic properties in hard/soft CoFe2O4/Fe3O4 nanocomposites

Abstract

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 (M_r/M_s), coercivity (H_c) 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.