Facile synthesis of porous coin-like iron and its excellent electromagnetic absorption performance

In this paper a novel electromagnetic absorbent, porous coin-like iron with a diameter of similar to 10 mu m and a thickness of 2 mm, was fabricated using a hydrogen gas reduction process. This special porous coin-like structure was attributed to a decrease in density and exceeded the Snoek limitation. It was observed that these coin-like iron structures exhibit excellent microwave absorption properties. An optimal reflection loss value of -53.2 dB was obtained at 16 GHz, moreover, the effective frequency bandwidth could be up to 6.3 GHz (11.7-18 GHz) at a thickness of 1.4 mm. The microwave absorption mechanism may have originated from the following factors: firstly, these coin-like irons were favorable for obtaining a lower real part of permittivity value and thus gained the improvement of impedance matching behavior, as compared with other reported irons. Secondly, the coin-like morphology exhibited a strong magnetic loss ability. Further analysis revealed that the magnetic loss mechanism may rely mainly on the resonance. In addition, the porous feature of the coin-like iron offered a rough surface on the large size of the coin-like structure, which was beneficial for electromagnetic wave scattering and further enhanced their microwave absorption properties.