Microwave Behavior of Polymer Bonded Iron Oxide Nanoparticles

Samples composed of a polymer matrix were loaded with different fractions from 0% to 30% of Fe oxide magnetic nanoparticles with an average size ranging from 5 to 25 nm. The permittivity and permeability of the composites were determined upon a very wide frequency range, spanning from DC to 30 GHz using different methods with overlapping frequency intervals. The nanoparticle content was observed to significantly modify the permeability and permittivity behavior of the polymer. The frequency and intensity of both dielectric and ferromagnetic resonances of the composites are clearly affected by the presence of the magnetic nanoparticles, and the composites can be optimized for specific applications requiring absorption of electromagnetic radiation from the MHz to the GHz range.