Electromagnetic-wave absorption properties of FeCo nanocapsules and coral-like aggregates self-assembled by the nanocapsules

FeCo nanocapsules with FeCo alloy as core and amorphous Al2O3 as shell have been synthesized by a modified arc-discharge technique. Three-dimensional coral-like aggregates are self-assembled by the nanocapsules in the arc-discharge process. The FeCo nanocapsules are ferromagnetic at room temperature. The electromagnetic-wave absorption properties of FeCo nanocapsules were investigated in the frequency range from 2 to 18 GHz. A reflection loss exceeding −20 dB was obtained in the frequency range of 5.2–15.9 GHz for absorber thicknesses of 2–4 mm. An optimal reflection loss of −44.8 dB was reached at 12.8 GHz for an absorber thickness of 3 mm. As a result, these FeCo nanocapsules may be applied in high-frequency electromagnetic-wave absorption.