Enhanced ultra-broadband electromagnetic wave absorption using liquid metal-coated carbonyl Fe/Ni microspheres with dual dielectric polarization

Abstract

Advanced broadband electromagnetic (EM) wave absorbers play a pivotal role in mitigating EM interference and radiation; however, achieving efficient attenuation across a wide frequency range remains a significant challenge. In this study, we present a novel synthesis method for core–shell hybrid microspheres by coating spherical carbonyl iron (Fe) and carbonyl nickel (Ni) particles with GaInSn liquid metal (LM), creating heterogeneous interfaces that effectively modulate the dielectric loss of the resulting EM absorber material. The dual heterogeneous interfaces formed between the Fe/Ni particles and LM coating were demonstrated to precisely control polarization losses, optimize impedance matching of the magnetic materials, and enable ultra-broadband EM wave absorption. These Fe/Ni@LM microspheres were subsequently integrated with polydimethylsiloxane (PDMS) to fabricate a flexible EM absorber, showcasing its practical capabilities. Under optimized LM content and absorber thickness, the carbonyl Fe/Ni@LM composite exhibited dual-peak EM wave absorption with an exceptional effective absorption bandwidth of 9.05 GHz (8.86–17.91 GHz), primarily spanning the X band and fully encompassing the Ku band, while achieving a remarkable minimum reflection loss of −54.73 dB. This study introduces a versatile strategy for incorporating multiple dielectric loss mechanisms into EM absorber design, ultimately enabling ultrawide absorption performance in Fe/Ni@LM composites synthesized via this innovative approach.