A MWCNT–nanoparticle composite as a highly efficient lightweight electromagnetic wave absorber in the range of 4–18 GHz

Abstract

A nanocomposite consisting of nanoparticles decorated by multi-wall carbon nanotubes (MWCNTs/Ag/Co_0.2Fe_2.8O₄) was designed and synthesized to meet requirements for a wider, thinner, and stronger electromagnetic (EM) wave absorber. The structure and morphology analysis revealed the structure of the nanocomposite absorber. The introduction of Ag nanoparticles can increase the interface by bringing stronger coupling into the heterogeneous nanocomposite, whereas Co_0.2Fe_2.8O₄ can introduce dipoles and magnetic loss as well as additional interfaces into the absorber. The electromagnetic parameters of absorber and wax composite with different absorber contents were measured in the range of 2–18 GHz to evaluate its EM wave attenuation performance. With an absorber loading of 20%, at a low thickness of 1.8 mm, the highest attenuation effectiveness value of −52.4 dB can be achieved at 10.2 GHz. Moreover, with absorber thicknesses from 1.1 to 3.7 mm, RL values below −20 dB can be achieved over a wide frequency range from 4.0 to 18 GHz covering the C band, the X band and the K_u band. Consequently, the nanocomposite absorber has an excellent EM wave attenuation ability with the characteristics of a wide absorption band (4–18 GHz), strong absorption (−52.4 dB) and low absorber thicknesses (1.1–3.7 mm). The excellent EM wave absorbency can be attributed to strong interfacial and dipole polarization, dielectric loss caused by Debye dipolar relaxation and the combination of dielectric loss and magnetic loss. Such a nanocomposite could serve as an attractive candidate for EM wave attenuation applications in the future.