Effects of orientation methods on electromagnetic parameters and microwave absorption characteristics of flaky carbonyl iron@SiO2 particles

In this study, flaky carbonyl iron powder (CIP)@SiO2 particle/polyurethane (PU) composites with different steric configurations were prepared using a rotating magnetic field and different cutting methods. The effects of the angle between the easy magnetization plane and the vector of incident electromagnetic (EM) waves on the EM parameters and microwave absorption characteristics were studied. In order to investigate the influences of different steric configurations of the flaky CIP@SiO2 particles on the EM parameters of the composites, the complex permeability of the samples was calculated using the Landau-Lifshitz-Gilbert equation and Bruggeman's effective medium theory combined with consideration of the shape anisotropy. The calculated results agreed well with the experimental results. In addition, it was revealed that the complex permeability of the composites was dominated mainly by the steric configuration of the flaky CIP@SiO2 particles, which was significant for the development of an excellent absorber in oblique incident conditions.