Structure and composition design on ternary CNT@ZnFe2O4@ZnO composite utilized as enhanced microwave absorbing materials

Abstract

As the increasing requirements on microwave absorber resulting from the complex application environment, composites consisting of multiple components have obvious superiority to the pure materials. In order to achieve excellent absorption performance for composites, both composition and microstructure should be properly designed. In this work, a three-phase composite consisting of conductive CNT, magnetic ZnFe2O4 and dielectric ZnO with coating structure is designed to enhance the microwave absorbing performance. The three-phase CNT@ZnFe2O4@ZnO composites are prepared by a two-step coprecipitation method. The as-prepared composite shows good impedance matching and high attenuation. When the content of ZnFe2O4 is 3 mmol, the composite has a reflection loss of −33.5 dB at 4.4 GHz. The huge interfaces area attributed to both the multi-phase component and multi-layer structure helps to improve the interface polarization, dipole polarization, multiple reflection and scattering. Besides, the synergy of the different loss mechanisms coming from the different materials can also effectively promote the absorption.