Electromagnetic-wave-absorption properties of wire-like structures self-assembled by FeCo nanocapsules

Al2O3-coated FeCo nanocapsules were synthesized by the arc-discharge method and three-dimensional wire-like macro-aggregates were self-assembled simultaneously by nanocapsules. The electromagnetic (EM) parameters (i.e. the relative permeability and permittivity) were measured at 2-18 GHz. As a consequence of the surface-and shape-anisotropy energy of the nanocapsules, a natural resonance at 6 GHz is dominant in the microwave absorption properties. A reflection loss (RL) exceeding - 20 dB was obtained in the frequency range 4.2-18 GHz for absorber thicknesses of 1.3-6 mm. An optimal RL of - 51 dB was found at 10.2 GHz for an absorber thickness of 2 mm. As a result, the Al2O3-coated FeCo nanocapsules show good prospects of being applied in EM wave absorptive devices.