Largely enhanced electromagnetic wave absorption via surface coating of carbonyl iron particles with liquid metal

Abstract

The significant benefits of heterointerfaces and their unique electromagnetic properties greatly enhance the design of advanced magnetic-matrix electromagnetic wave absorbers. However, achieving quicker and simpler fabrication of heterogeneous interfaces for high-performance electromagnetic wave (EMW) absorbing materials remains a significant yet challenging research focus. Herein, we present a novel method for preparing core–shell hybrids by applying a GaInSn liquid metal (LM) coating on spherical carbonyl iron particle (CIP) surfaces, which creates a heterogeneous interface that adjusts dielectric loss. The results indicate that these heterointerfaces can efficiently control polarization losses, balance impedance matching in magnetic materials, and boost electromagnetic wave absorption. Only 5 wt% coating on the surface of CIPs could result in an optimal reflection loss of −65.94 dB at a thickness of 1.96 mm, which is 3.9 times greater than that of carbonyl iron with the same mass, taking PDMS/CIP composites as an example. Density functional theory calculations revealed a buffer layer that enhances electron transfer and charge balance, improving polarization and EMW absorption. Furthermore, the radar cross-section simulation results illustrate that CIP@LM efficiently reduces EMW scattering and transmission on fighter aircraft, indicating its excellent practical application potential. The findings of this study clarify the complex interplay between the metal–metal heterointerface and EMW dissipation, elucidating the mechanism behind the impedance matching of magnetic materials.