Facile synthesis of BaTiO_3 on multiwalled carbon nanotubes as a synergistic microwave absorber

摘要

Microwave absorbing composites composed of both multi-walled carbon nanotubes (MWCNTs) and Barium titanatena (BaTiO_3) nanoparticles as absorbers were prepared by sol-gel method. The structure and morphology of the BaTiO_3/MWCNTs nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The complex permittivity and permeability of the BaTiO_3/MWCNTs nanocomposites were measured and then the reflection loss (RL) was calculated in the frequency range of 1-18 GHz. The sample ω_m = 2.5 % (the mass fraction of MWCNTs is denoted as ω_m hereafter) has the minimum reflection loss of -34.4 dB at 15.1 GHz compared with the other samples at the same thickness of 1.4 mm and the effective band-width(RL ＜ -10 dB) is even wider than 3.5 GHz, ranging from 13.8 to 17.4 GHz. Furthermore, the sample ω_m = 2.5 % can reach -47.9 dB at 7.1 GHz with the thickness of 7.0 mm and the effective bandwidth almost covers 10 GHz with the thickness ranging from 1.4 to 9.0 mm. The obtained BaTiO_3/MWCNTs nanocomposites may become an ideal microwave absorber with thin thickness, broad bandwidth and strong absorption. Good absorption properties at a low MWCNTs loading provide an added advantage in terms of ease of processability, MWCNTs filler saving and overall process economics.