Enhanced broadband microwave reflection loss of multiwalled carbon nanotubes (MWCNTs)/bismuth ferrite hybrid composites

Abstract

The accelerated growth of high-frequency electronic devices has increased concerns over electromagnetic interference (EMI), generating a strong need for lightweight and broadband electromagnetic (EM) absorbing materials. Bismuth ferrite (BiFeO3, BFO) is a multiferroic material for EM absorption due to its coupled ferroelectric and antiferromagnetic properties. However, its performance is constrained by high leakage current, large dielectric loss, narrow absorption bandwidth, and the need for high filler loading in composite systems. To address these challenges, this study introduces a hybridization approach by combining BFO with multiwalled carbon nanotubes (MWCNTs) to improve dielectric–magnetic balance and enhance EM attenuation. MWCNTs were synthesized using BFO nanoparticles as catalysts and ethanol as the carbon source via a chemical vapor deposition (CVD) method. The resulting MWCNTs–BFO hybrid powders were incorporated into an epoxy matrix at low filler content and characterized for their microwave absorption properties in the 8–18 GHz frequency range. The hybrid system demonstrated a strong synergistic effect, leading to enhanced dielectric loss, improved impedance matching, and efficient multi-scattering attenuation. The MWCNTs-BFO/epoxy composite achieved more than 99% microwave absorption with an effective bandwidth of 4.6 GHz using only 4 wt% filler. These results confirm that MWCNTs–BFO hybrids offer a promising pathway for developing next-generation, lightweight, and high-performance microwave absorbing materials.