Effect of surfactant on the microstructure and microwave-absorbing properties of helical carbon nanotubes/doped barium ferrite composites

Abstract

Doped barium ferrite/helical carbon nanotube composites were prepared using a sol-gel method. The microstructure of doped barium ferrite/helical carbon nanotube composites treated with different surfactants was analyzed using scanning electron microscopy, Nanoparticle potentiometer, specific surface and porosity analyzer, ultraviolet-visible spectrometer, cold field emission scanning electron microscope, and X-ray diffraction. The electromagnetic parameters and absorption properties of the composites were analyzed using a vector network analyzer, and the enhancing mechanism of the absorption properties of doped barium ferrite/helical carbon nanotube composites was studied. The results show that the barium ferrite particles and carbon nanotubes in the composite material are overlapped through the sheet-line and sheet-sheet interactions, which results in a rich microcavity structure and a good conductive network. The composites treated with sodium dodecyl sulfate (SDS, 10 g/L) exhibit good potential difference and system stability due to the combination of electrostatic repulsion, van der Waals attraction, space repulsion, and vacancy repulsion. The composite treated with SDS exhibits the strongest return loss (−56.84 dB at 3.12 GHz with a matching thickness of 3.12 mm) among all composites. It also has a wide absorption frequency band of 6.34 GHz, which covers the Ku band with a matching thickness of only 1.44 mm. The main loss mechanisms are polarization relaxation, multiple scattering of electromagnetic waves, conduction loss, natural resonance, and domain wall resonance.