Dielectric, magnetic, and microwave absorbing properties of Ag-plated terapod-like ZnO whiskers

Thin thickness, lightweight, wideband and high absorption intensity are highly desirable properties for the next-generation electromagnetic wave absorbing materials. This study investigates the dielectric, magnetic, and microwave absorbing properties of terapod-like ZnO whisker (ZnOW) modified by Ag nanocrystals (Ag-ZnOW), synthesized by vacuum evaporation method. The complex permittivity and permeability were measured at a microwave frequency range of 2-18 GHz. Ag nanocrystals plated on the surface of whiskers enhance the magnetic loss of ZnOW. The Ag-ZnOW possesses much broader bandwith of absorbing peak than that of unplated ZnOW. The maximum reflectivity (R) is about -30.27 dB at 11.40 GHz and the corresponding bandwidth below -10 dB is more than 5.25 GHz with a matching thickness of 3.0 mm. The calculated results show that the peak of R shifts to lower frequency region with the increase of thickness, and the Ag-ZnOW is an excellent candidate for designing lightweight and multipurpose microwave absorbers.