The design of core–shell-structured Fe@Sm2Fe17 dual magnetic nanoparticles for high-performance electromagnetic wave absorption

The magnetic loss plays a key role in electromagnetic waves (EMW) absorption. However, the magnetic loss ability would obviously draw at high frequency, and the component lacks the dielectric loss ability, resulting in poor EMW absorption. In this work, we design a core–shell-structured Fe@Sm₂Fe₁₇ dual magnetic nanoparticle. The 200-nm Sm₂Fe₁₇ nanoparticles play a key role in maintaining relatively high magnetic loss ability even at high frequency. And the introduction of 3-μm Fe cubes can optimize the dielectric parameters by the interface polarization and thus enhance the impedance matching. Meanwhile, Fe cubes with easy axis vertical to six planes can absorb the EMW with different directions, leading to the enhancement of the EMW attenuation. Especially, the Fe cubes can align the moment of Sm₂Fe₁₇ nanoparticles, which can increase exchange-coupling interaction between them to further improve the magnetic loss capacity and broaden the effective absorption bandwidth (EAB). Furthermore, the small-sized Sm₂Fe₁₇ nanoparticles provide a rough surface, which promotes multiple reflections and scattering of the incident EMW. As a result, the optimal EMW attenuation performance with a minimum reflection loss exceeding −51.4 dB and a broadened EAB up to 6.6 GHz at 1.4 mm was achieved in Fe@Sm₂Fe₁₇ composites with Sm/Fe of 1:12. Our work provides profound insights into developing well-coordinated magnetic–dielectric nanocomposites for EMW absorption engineering.

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