科研之友
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摘要
In this work, core-shell shaped Fe3O4@C composites have been firstly prepared by in-situ polymerization of phenolic resin on the surface of Fe3O4 and subsequent high-temperature carbonization. The core of Fe3O4 nanoparticles can be partial or totally reduced to metallic Fe in a N-2/H-2 atmosphere and resulted in Fe3O4-Fe@C and Fe@C products. These as-prepared Fe-Fe3O4@C and Fe@C products are analyzed by X-ray diffraction (XRD), and transmission electron microscopy (TEM). Furthermore, the electromagnetic microwave absorption properties of the core-shell nanocomposites are investigated in terms of the theory of transmission lines. Compared with pristine Fe3O4, Fe3O4@C and Fe@C, the Fe3O4-Fe@C ternary heterostructures exhibit the outstanding microwave absorption properties. The minimum reflection loss (RL) of -29.3 dB can be observed at the frequency of 12.6 GHz with the thickness of 3.9 mm. The bandwidth (RL <= - 10 dB) can be monitored in the frequency of 3.6-18 GHz with the thickness of 1.5-4.0 mm. The excellent absorption is attributed to the synergistic effect of dielectric and magnetic loss, multiple interfacial polarization resonances, and good impedance match.
