Dual nonlinear dielectric resonance and strong natural resonance in Ni/ZnO nanocapsules

The electromagnetic characteristics of Ni/ZnO nanocapsules were studied at 2-18 GHz. The dual nonlinear dielectric resonance and strong natural resonance at 16.6 GHz contribute to excellent electromagnetic absorption. A reflection loss (RL) exceeding -20 dB was calculated in 14-18 GHz for an absorber thickness of 2.05 mm, and RL exceeds -10 dB in the whole X-band (10-12.4 GHz) and the whole Ku-band (12.4-18 GHz) for a thickness of 2.50 mm. The equivalent circuit model was used to explain the dual nonlinear dielectric resonance, which is ascribed to a cooperative consequence of the core/shell interfaces and the dielectric ZnO shells.