Synthesis and microwave-absorbing properties of Al2O3 coated polyhedral Fe nanocapsules prepared by arc-discharge method

Al2O3 coated polyhedral Fe nanocapsules were prepared by arc-discharging a Fe-Al(8at%Al) alloy. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy, and network analyzer were employed to investigate the microstructures, compositions and electromagnetic properties (2-18GHz). The reflection loss R(dB) of the nanocapsules reaches to -50.5dB at 7.90Hz with a 3mm thickness, and EM absorption properties(RL<-20dB) in the 5.2 similar to 16.1GHz range with thickness range of 1.67-4.7mm. The excellent Microwave-absorption properties of as-prepared nanocapsules are ascribed to shape anisotropy and core/shell structure.