Synergistic Enhancement of Magnetic–Dielectric Response in the FeCo₂O₄-Modified SiC_f Composites for Efficient Microwave Absorption

Stable silicon carbide fibers (SiC_f) have the potential to be utilized in microwave absorption (MA) applications. However, the low complex permittivity and absence of magnetic loss of SiC_f result in impedance mismatching and a narrow absorption bandwidth. The development of SiC_f-based composites exhibiting multiple electromagnetic loss mechanisms and excellent impedance matching represents a significant challenge, yet is of great importance. In this study, a magnetic FeCo₂O₄ nanoparticle-modified SiC_f composite (FCO@SiC_f) was synthesized by the frequently employed hydrothermal method. An investigation was conducted to examine the microstructure, morphology, dielectric-magnetic responses, and microwave absorption properties of the material in question. Furthermore, the mechanisms of action were subjected to further analysis. By varying the concentration of FeCo₂O₄ nanoparticles, the frequency dependence of the electromagnetic parameters of the FCO@SiC_f composite was effectively modified in order to tune the impedance matching. It was demonstrated that the FCO@SiC_f composite, with a loading of only 20 wt.% FeCo₂O₄, exhibited a remarkably wide effective absorption bandwidth (EAB, RL < −10 dB) of 6.16 GHz and an impressive reflection loss (RL_min) of up to −34.51 dB, respectively. These findings suggest that the FCO@SiC_f composites have considerable potential for application in the domain of microwave absorption.