In this study, a novel absorber with a high performance microwave absorption property was prepared by innovatively coupling flaky carbonyl iron (FCI) and reduced graphene oxide (rGO) nanosheets into a homogenous composite. The rGO nanosheets are tightly coated on the surface of FCI, which gives typical dielectric dispersion behavior of complex permittivity and resultantly optimizes characteristic impedance matching. Meanwhile, the introduction of rGO as a dielectric lossy material endows FCI with improved dielectric loss ability and unfading magnetic loss ability. In the frequency range of 2.0-18.0 GHz, the rGO-coated FCI composite gives a minimum value of reflection loss with -65.4 dB at 5.2 GHz when the absorber thickness is 3.87 mm and always shows effective bandwidth under -20 dB when absorber thickness is from 1.5 mm to 5 mm. The contribution of typical dielectric dispersion behavior in rGO-coated FCI is demonstrated by a delta-function method to characteristic impedance matching and the excellent microwave absorbing performance.
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