A Graphitic Carbon/La−Ni−Co−Mg Mixed Oxide Nanocomposite for Electromagnetic Wave Absorption

Abstract

Graphitized carbon-based composites are prone to severe skin effects on incident electromagnetic waves due to their high electrical conductivity, which leads to impedance mismatch and limits their wave-absorbing performance in the 2−18 GHz frequency range. To address this bottleneck, this study presents a synergistic strategy that couples large-ionic-radius lanthanum doping with combustion-driven synthesis to construct multi-phase oxide/carbon composites for efficient electromagnetic wave absorption. Through a three-step process of impregnation−combustion−annealing, defect-rich carbon-based composites were successfully prepared, achieving efficient electromagnetic wave absorption in the X-band. The enhancement in performance can be attributed to the introduction of the rare-earth element La. Owing to its large ionic radius and high charge density, La induces lattice distortion and charge imbalance when substituting at transition-metal sites, stabilizes oxygen vacancies, and provides additional dipolar polarization relaxation loss channels, significantly improving polarization loss capability. Experiments show that the combustion-assisted La-doped samples achieved excellent electromagnetic balance in the 2−18 GHz frequency range, with a minimum reflection loss (RLmin) reaching −57.01 dB, an increase of 230.3% compared with undoped samples. This strategy opens an avenue for designing high-performance carbon-based wave-absorbing materials.