Electromagnetic and microwave-absorbing properties of magnetite decorated multiwalled carbon nanotubes prepared with poly(N-vinyl-2-pyrrolidone)

The magnetite (Fe3O4) decorated multiwalled carbon nanotubes (MWNTs) hybrids were prepared by an in situ chemical precipitation method using poly(N-vinyl-2-pyrrolidone) (PVP) as dispersant. The structure and morphology of hybrids are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron-microscopy (TEM). The TEM investigation shows that the Fe3O4/MWNTs hybrids exhibit less entangled structure and many more Fe3O4 particles are attached homogeneously on the surface of MWNTs, which indicated that PVP can indeed help MWNTs to disperse in isolated form. The electromagnetic and absorbing properties were investigated in a frequency of 2-18 GHz. The results show that the Fe3O4/MWNTs hybrids exhibit a superparamagnetic behavior and possess a saturation magnetization of 22.9 emu/g. The maximum reflection loss is -35.8 dB at 8.56 GHz, and the bandwidth below 10 dB is more than 2.32 GHz. More importantly, a new reflection loss peak occurs at the frequency of 14.6 GHz, which indicates that the Fe3O4/MWNTs hybrids have better absorption properties in the high-frequency. (C) 2011 Elsevier Ltd. All rights reserved.