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 are crucial for reducing EM interference and radiation. However, achieving efficient attenuation across a wide range of frequencies remains challenging. A novel approach for synthesizing core–shell hybrid microspheres was demonstrated in this study by coating spherical carbonyl iron Fe and carbonyl Ni particles with GaInSn liquid metal (LM) to form heterogeneous interfaces capable of adjusting the dielectric loss of the resulting EM absorber material. The dual heterogeneous interfaces between the Fe and Ni particles and LM coating were shown to effectively control polarization losses, ensure balanced impedance matching of the magnetic materials, and facilitate ultra-broadband EM wave absorption. These Fe/Ni@LM microspheres were composited with polydimethylsiloxane to prepare and demonstrate the capabilities of a flexible EM absorber. Using the optimal LM content and absorber thickness, the carbonyl Fe/Ni@LM exhibited dual-peak EM wave absorption over a broad effective absorption bandwidth equal to 9.05 GHz (8.86–17.91 GHz), primarily within the X band and fully covering the Ku band and achieved a minimum reflection loss of −54.73 dB. Thus, this study proposed a flexible strategy for integrating multiple dielectric loss mechanisms into the design of EM wave absorbers to realize an ultrawide absorption of the Fe/Ni@LM prepared using this approach.