Correlations between shape/size/oxidation of iron particle and electromagnetic properties of Fe-silicone rubber composites

Abstract

Iron (Fe) powders with high-purity and controlled primary and secondary assembled particles were synthesized with reduction process to control the particle shape and thereby variation of its electromagnetic properties. Iron precursors, such as iron hydroxide and iron oxide powder precursors, with fine-sized and acicular or spherical/cubic morphology, were prepared by co-precipitation and hydrothermal processes and then reduced at different reducing atmospheres by using a hydrogen/argon mixed gas. The electromagnetic properties were evaluated by dielectric permittivity and magnetic permeability and their loss measurements. The reduced Fe powders showed different particle shapes and sizes with different reduction conditions, which affected both primary and secondary particles and thereby electromagnetic properties. The morphology of the Fe powders strongly depended on the reduction conditions and precursor's morphology. The electromagnetic properties were varied with different shapes and sizes of primary and secondary particles. It was found that the permeability is better for interconnected secondary particles with smaller primary particle size, and the dielectric permittivity is much more variable than the magnetic permeability with different parameters mentioned above.