Trilayer Core–Shell FeCo@SiO2@Lithium–Aluminum–Silicate Microspheres for Electromagnetic Wave Absorption

The poor impedance matching characteristics of FeCo alloy nanoparticles severely restrict its development with higher efficiency, wider bandwidth, and stronger absorption materials. The main strategy for addressing this issue is to design core–shell structures to adjust the electromagnetic parameters and impedance matching. Currently, the research of core–shell structures primarily focuses on composites of magnetic/single wave-transparent/dielectric materials, with limited research on synergistic modifications of multiple wave-transparent components in magnetic nanomaterials for enhanced electromagnetic wave absorption. Here, a trilayer core–shell structure FeCo@SiO2@lithium–aluminum–silicate glass-ceramic (LAS) nanoabsorber was successfully fabricated via the sol–gel method in a kinetically controlled manner, which exhibited fascinating electromagnetic wave absorption performance with a minimum reflection loss of −50.90 dB and a maximum effective absorption bandwidth of 7.52 GHz. The results confirm that the modulating effects of the FeCo core on electromagnetic wave absorption performance for SiO2 at low frequency and LAS at high frequency can be coupled and superimposed. This study demonstrates the potential of magnetic nanomaterials modified by incorporating multiple wave-transparent components, while providing insights for the development of lightweight and wide effective bandwidth nanoabsorbers.