Engineering Double Core−Shell Heterointerfaces in Sm2TM17-Based Nanocomposites for Enhanced Microwave Absorption

Sm2TM17 alloys (where TM = Co, Fe, Cu, or Zr), with high saturation magnetization and strong magnetocrystalline anisotropy, have shown great promise for microwave absorption. However, their chemical instability during composite fabrication severely impedes synergistic coupling with dielectric materials. Herein, a core−shell structured Sm2TM17@SiO2@ReS2 nanocomposite with multiple nano-heterointerfaces was successfully fabricated via a SiO2 interlayer strategy combined with hydrothermal in situ growth of ReS2 nanosheets. The SiO2 shell significantly suppresses the large-scale sulfidation of Sm2TM17, thereby maximally preserving its intrinsic magnetic properties. Moreover, the unique hierarchical core−shell architecture creates abundant nano-heterointerfaces between the Sm2TM17 magnetic core and the ReS2 dielectric shell, which not only enhances interfacial polarization but also optimizes impedance matching and enables strong magnetic-dielectric synergistic loss. Consequently, the nanocomposite delivers outstanding microwave absorption performance, achieving a maximum effective absorption bandwidth of 6.16 GHz and a minimum reflection loss of −47.54 dB. Radar cross-section simulations further demonstrate its practical applicability. This work provides a valuable reference for the design of broadband microwave-absorbing materials based on rare-earth permanent magnets.