Core/Shell Iron/Oxide Nanoparticles for Improving the Magneto-Dielectric Properties of Polymer Composites

Abstract

A simple method to obtain high magnetic permeability (μr), high dielectric permittivity (εr), and low loss polymer composites with core/shell iron/metal oxide particles is developed. Magnetic iron (Fe0) particles with protective SiO2 shells are synthesized in aqueous environment at room temperature. The shells provide electrical insulting layers which decrease energy loss and also prevent the possibility of μr decrease due to Fe0 oxidation. Furthermore, Fe0 particles could also be coated with TiO2 shells which allow εr to be tuned. The εr and μr of the resulting polydimethylsiloxane composites are optimized for core-shell particle doping. The value of εr is up to 9.8 and most importantly, the μ is close to 2 at 1 GHz with 43 wt% doping of core-shell particles. The dielectric loss of the composites is less than 0.02.