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Carbon-encapsulated Fe-Co alloy nanoparticles (Fe-Co(C)) have been fabricated with different Co/Fe ratios by an efficient solid-state route using melamine as carbon source. The structure and morphology of Fe-Co(C) nanoparticles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The XRD characterization results reveal that all products are alloys with no carbide impurity. The TEM and HRTEM observations show that the alloy nanoparticles are encapsulated in carbon shells. Additionally, the reactions involved in the syntheses are postulated. The variation of magnetic properties of Fe-Co(C) with Co/Fe has been discussed according to the room temperature VSM measurement results.

Nanocomposites of Fe-Co alloy and cobalt-substituted magnetite magnetic materials Fe x Co 1-x /Co y Re z Fe 3-y-z O 4 (Re ) none, La, Nd, and Gd) have been obtained successfully employing a surfactant-assisted solvothermal method. The nanocomposite features hard and soft magnetic phases juxtaposed within one discrete, anisotropic structure. Sodium oleate molecules were found effective in preventing the oxidation of the Fe-Co alloy and aggregation of the magnetic microspheres. X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy were used to characterize the structure and the morphology of the products. The result of magnetic characterization reveals that the magnetic microspheres exhibit a ferromagnetic behavior and possess high saturation magnetization and low coercivity. It is expected that these magnetic microspheres with uniform size would have potential applications such as magnetic carriers for drug targeting because of their excellent soft-magnetic properties.