Microwave-absorption properties of ZnO-coated iron nanocapsules

The electromagnetic (EM) characteristics of ZnO-coated Fe nanocapsules synthesized by arc discharging were studied at 2-18 GHz. A reflection loss (RL) exceeding -20 dB was obtained in the frequency range of 6.1-15.7 GHz for an absorber thickness of 1.5-5 mm. An optimal RL of -57.1 dB was found at 7.8 GHz for an absorber thickness of 3.00 mm. 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. (c) 2008 American Institute of Physics.