Excellent microwave absorption properties of the h-BN-GO-Fe3O4 ternary composite

A ternary composite of hexagonal boron nitride nanoplates-graphene oxide-Fe3O4 microplates (h-BN-GO-Fe3O4) as a novel type of electromagnetic (EM) microwave absorbing material was synthesized via a facile and efficient strategy. The composite has a layered microstructure with interlayer voids. The GO layers and h-BN nanoplates can significantly reduce the aggregation of the Fe3O4 microplates to reduce conductivity. The overlapped Fe3O4 microplates and the embedded h-BN nanoplates result in voids which further increase the resistivity of the material and suppress eddy current effectively. The hierarchically multicomponent structure is in favor of improving the impedance matching and results in excellent EM microwave absorbing performance. An effective absorption bandwidth (RL < -10 dB) of 12.2 GHz is achieved when the absorber thicknesses range from 2.0 to 5.0 mm. The EM microwave absorption mechanism of the composite is discussed using a complex thickness model and the quarter-wavelength cancellation theory. It is found that the remarkable microwave absorption performances can be ascribed to the joint outcome of the interfacial cancellation of the incident and reflected EM microwaves at the air-material interface and the dissipation of the microwaves via magnetic loss, multiple reflections and scattering in the material. This research demonstrates void containing composites as an efficient approach for fabricating broad-bandwidth and efficient EM microwave absorbers.