Microwave-absorption properties of ZnO-coated iron nanocapsules

The electromagnetic (EM) characteristics of ZnO-coated Fe nanocapsules synthesized by arc discharging were studied at 2–18GHz. A reflection loss (RL) exceeding −20dB was obtained in the frequency range of 6.1–15.7GHz for an absorber thickness of 1.5–5mm. An optimal RL of −57.1dB was found at 7.8GHz for an absorber thickness of 3.00mm. The excellent microwave-absorption properties are a consequence of a proper EM match in the nano-microstructure, a strong natural resonance, as well as multipolarization mechanisms. ZnO-coated Fe nanocapsules may be attractive candidates for EM-wave-absorption materials.