Nonpolar Solvothermal Fabrication and Electromagnetic Properties of Magnetic Fe3O4 Encapsulated Semimetal Bi Nanocomposites

Magnetic Fe3O4 nanoparticles (NPs) encapsulated semimetal Bi nanocomposites were fabricated by a solvothermal method based on the nonpolar 1-octadecene. Bi and Fe ions were introduced into the oil phase by the complex with sodium oleate in the as-prepared solution. The nanocomposites were oil soluble and dispersed well in any nonpolar solution with the surface modification of oleic acid. It is argued that hydroxyl groups as the reductant induce the formation of Bi microspheres and prevent Fe3O4 NPs from oxidation. The frequency dependence of complex permittivity and permeability indicates that Bi and interface polarization of Bi/Fe3O4 nanocomposites are responsible for the dielectric resonances, and superparamagnetic Fe3O4 NPs weaken the natural resonance.