In-situ growth of Fe/Fe₃O₄/C hierarchical architectures with wide-band electromagnetic wave absorption

Carbon materials have aroused extensive interests for their remarkable electrical properties as electromagnetic wave (EMW) absorption. However, the synthesis of the wide-band electromagnetic wave absorbent is an insuperable challenge for attaining effective refection loss and electromagnetic matching. Herein, a facile method for large-scale synthesis of monodispersed Fe/Fe₃O₄/C composite microspheres is proposed. The carbon microspheres (1–2 µm in diameter) imbedded with nanosized Fe/Fe₃O₄ particles (10–20 nm) are uniformly produced by polymerization and carbothermic reduction processes. The products exhibit the minimum refection loss −45.5 dB at 9.4 GHz and a broad bandwidth of 4.1 GHz below −10 dB from 7.8 GHz to 11.9 GHz with a thickness of 3.0 mm. The absorption mechanism indicates a unique deviated Debye dipolar relaxation effect in the absorbing bandwidth.