Magnetic Properties Of CoFe₂/CoFe₂O₄ Nanocomposite

CoFe₂/CoFe₂O₄ metal/oxide composite was fabricated by sol-gel method and subsequent partly reducing process. XRD patterns show the samples contain spinel cobalt ferrite phase and bcc CoFe₂ phase. The proportion of CoFe₂O₄ to CoFe₂ phase diminishes with the increasing of reducing time. SEM photos indicate CoFe₂ /CoFe₂O₄ nanocomposite has a coral like microstructure which can join many grains together. Magnetic properties measurements indicate that both the specific saturation magnetization and coercivity of the composites increase with respect to the precursor of pure CoFe₂O₄ nanoparticles. The enhancement of magnetization is ascribed to the presence of CoFe₂ with relatively higher magnetization. The larger coercivity of the composites can be explained with the enhancement of thermal stability of magnetic moments, which can be proved by Mossbauer spectra. Consequently, we believe that this method can lead to a new route for the improvement of quality of nano magnetic materials.