Effects of Al content in Fe–Al raw material alloy on shape and microwave absorption of Fe-based nanocapsules prepared by arc discharged method

Abstract

In this study, the three types of core–shell structured Fe-based nanocapsules with different shapes were synthesized using arc-discharge method via fine-tuning Al content in Fe–Al raw material alloy. The synthetic parameters on the microstructure and shape as well as microwave absorption properties of Fe-based nanocapsules were investigated in detail. The results show that the Al content in Fe–Al raw material alloy will affect the shape and microwave absorption properties of the synthesized Fe-based nanocapsule absorbent. The polyhedral Fe@FeOx–Al2O3 nanocapsules absorbents can be obtained while Fe–Al raw material alloy containing Al 3 wt% was used as an anode in arc-discharge process, and their microwave absorption properties can be significantly improved, compared with those of the prepared other two Fe-based nanocapsules. Reflection loss (RL) values below − 20 dB for polyhedral Fe@FeOx–Al2O3 nanocapsules absorbent are acquired in the frequency range of 3.21–18 GHz within 1.2–5.5 mm thickness, covering few S-bands and whole C–Ku bands. Besides, the FexAly phase existed in Fe-based nanocapsules cause the frequency band of the strongest RL (exceeding − 20 dB) shifting low-frequency region, which can be of help in further researching microwave absorption (L–S wave band) of FexAly alloy or other Al-magnetic transition metal nanoparticles absorbent in future work. These results demonstrate that the polyhedral Fe nanocapsules hold excellent microwave absorption properties, which could be promising candidate materials for the manufacture of microwave devices with broadband.