Dielectric and magnetic properties of Fe@FexOy/epoxy resin nanocomposites as high-performance electromagnetic insulating materials

The (Fe@FexOy)/epoxy resin (ER) composites are fabricated and their dielectric and magnetic properties are systematically investigated in order to acquire the high-performance electromagnetic insulating materials. Fe@FexOy nanoparticles with core–shell structure are prepared using an oxidation process. The thickness of FexOy shell and soft magnetic properties of Fe@FexOy nanoparticles can be controlled by adjusting the oxidizing temperature (Tox). The FexOy shell benefits the reduction of eddy current and the improvement of breakdown strength in their ER composites. With increasing Tox, the dielectric constant of the composites increases because of the enhancement of duplex interfacial polarization. Besides, the real part of the complex magnetic permeability has a slight decrease, which might be due to the more domain wall movement.