Enhanced electromagnetic characteristics of carbon nanotubes/carbonyl iron powders complex absorbers in 2-18 GHz ranges

The electromagnetic (EM) characteristics of the carbon nanotubes/carbonyl iron powders (CNTs/CIPs) complex absorbers synthesized by mixing CNTs with CIPs were studied at 2-18 GHz, for the aim of the absorbing coating with thinness, lightness, width, and strength. Compared with CIPs, the CNTs/CIPs composites had higher electrical conductivity, permittivity, and dielectric loss, which gradually increased with the increasing CNTs content (Waifs). Among them, with W-CNTs = 2.2%, a reflection loss (R-L) exceeding -20 dB was obtained in the frequency range of 6.4-14.8 GHz for a coating thickness of 1.2-2.5 mm. Particularly, a minimum R-L of 33.3 dB was found at 11.2 GHz corresponding to a matching thickness of 1.5 mm. The excellent EM-wave absorption properties are a consequence of a proper EM matching and enhanced absorption abilities resulting from the addition of a small quantity of CNTs with high electrical conductivity, permittivity, and dielectric loss. Thus, CNTs/CIPs complex absorbers may be promising candidates for EM-wave-absorption materials with strong-absorption, thin-thickness, light-weight, and low-cost. (C) 2010 Elsevier B.V. All rights reserved.