Optimization of Fe@Ag core-shell nanowires with improved impedance matching and microwave absorption properties

Ag-coated Fe (Fe@Ag) core-shell nanowires (NWs) with enhanced electromagnetic wave absorption were successfully synthesized by the liquid-phase reduction method and the layer-plus-island growth mode. Changing the molar ratio of Fe to Ag controlled the Ag shell thickness to produce different impedance matching and attenuation constants of the Fe@Ag core-shell NWs. The Fe@Ag core-shell NWs with a Fe:Ag ratio of 2:1 significantly improved optimal microwave absorption performance as compared to raw Fe NWs. At a mass fraction of 25%, the minimum reflection loss (RLmin) can reach - 58.69 dB at 7.53 GHz with a matching absorber thickness of 3.36 mm. In addition, the effective absorption bandwidth (EAB, RL <= - 10 dB) can be extended to 7.32 GHz, to cover the majority of the C and X bands. Three major aspects contribute to the superior microwave absorption performance: the complementary effect of the polarization of Fe-Ag interface, the impedance matching improvement stems from a proper eddy current, and the small-scale effect caused by a one-dimensional structure. This study demonstrates the promising high-efficiency microwave absorbing capabilities of Fe@Ag core-shell NWs for future use in practical applications.

Automated summary

Fe@Ag core-shell nanowires with enhanced electromagnetic wave absorption were successfully synthesized, with different Ag shell thickness controlled by changing Fe to Ag molar ratio to improve impedance matching and attenuation constants. The Fe@Ag core-shell nanowires show promising high-efficiency microwave absorbing capabilities due to the complementary effect of the Fe-Ag interface polarization, impedance matching improvement, and small-scale effect caused by the one-dimensional structure.