Search

• Fe-C core-shell nanoparticles were fabricated with excellent comparability in the graphitization degree of C shells. • The influences of C shell graphitization degree on metal-C nanoparticles' electromagnetic properties were clarified. • The threshold value of 1 / ω determines the nonlinear behavior of polarization loss. • Effective bandwidth of 9.0 GHz and optimal reflection loss of -59.9 dB were obtained. In this study, Fe-C core-shell nanoparticles with identical metal core sizes and C shell thicknesses but varying degrees of graphitization of C shells were fabricated using metal-organic chemical vapor deposition and subsequent annealing. Due to the identical metal core, these nanoparticles exhibite a similar permeability, but significantly varying permittivity depending on how much C shells have been graphitized. It was discovered that proper graphitization of Fe-C nanoparticles annealed at 1350 °C can produce excellent microwave absorption (MA), decent dielectric loss tangent in high frequency region, and moderately strong dielectric loss and attenuation properties. Furthermore, the threshold value of 1 / ω is discovered to be a crucial parameter in the theoretical analysis of nonlinear behavior of polarization loss, and thus MA performance of the nanoparticles. This research offers a useful method for creating metal-C nanoparticles with various levels of C shell graphitization. It also provides a clear answer to the crucial question of how the level of C shell graphitization affects the MA performance of metal-C nanoparticles. These results may serve as a reference for the development and mechanism analysis of highly effective metal-C based absorbers. Synthesis of Fe-C core-shell nanoparticles with tunable degree of graphitization in the C shells and elucidation of the influence of graphitization degree on the microwave absorption performance of the nanoparticles. [Display omitted] [ABSTRACT FROM AUTHOR]