Optimization on microwave absorbing properties of carbon nanotubes and magnetic oxide composite materials

摘要

Highlights•Microwave absorbing coefficient is defined, and its expression is derived by electromagnetic theory.•Optimization on the ratio of carbon nanotubes to nickel ferrite is carried out by microwave absorbing coefficient with magnetic parameters.•Real part of complex permeability has more obvious effect on absorbing properties than imaginary part.AbstractBased on the physical principle of interaction between electromagnetic field and the electromagnetic medium, the relationship between microwave absorbing coefficient (MAC) and the electromagnetic parameters of materials was established. With the composite materials of nickel ferrite (NiFe2O4), carbon nanotubes (CNTs) and paraffin as an example, optimization on absorbing properties of CNTs/magnetic oxide composite materials was studied at the frequency range of 2–18 GHz, and a conclusion is drawn that the MAC is the biggest at the same frequency, when the CNTs is 10 wt% in the composite materials. Through study on the relationship between complex permeability and MAC, another interesting conclusion is drawn that MAC is obviously affected by the real part of complex permeability, and increasing real part of complex permeability is beneficial for improving absorbing properties. The conclusion of this paper can provide a useful reference for the optimization research on the microwave absorbing properties of CNTs/ferrite composite materials.