The electromagnetic characteristics and absorbing properties of multi-walled carbon nanotubes filled with Er2O3 nanoparticles as microwave absorbers

Multi-walled carbon nanotubes (MWCNTs) filled with Er2O3 were synthesized by wet chemical method. Their electromagnetic characteristics and microwave absorbing properties were investigated in the frequency range of 2-18 GHz. The complex permittivity and electric loss tangent of Er2O3-filled MWCNTs demonstrate a decreasing trend while the complex permeability and magnetic loss tangent are larger than those of the unfilled MWCNTs. The Er2O3 nanoparticles encapsulated in the cavities modulate the electromagnetic parameters of MWCNTs, and thus affect the microwave absorbing properties. The modified MWCNTs possess much broader absorbing bandwidth and larger reflectivity than those of unfilled MWCNTs. With the increase of thickness, the peak value of reflectivity shifts to lower frequencies and multiple absorbing peaks appear. The result of calculation indicates that Er2O3-filled MWCNTs have potential applications in thin thickness and light-weight microwave absorbers. (C) 2008 Elsevier B.V. All rights reserved.