Microstructure and microwave absorption properties of carbon-coated iron nanocapsules

Carbon-coated Fe [Fe(C)] nanocapsules were synthesized by a modified arc-discharge method, and their microstructure and electromagnetic (EM) properties (2–18 GHz) were investigated by means of transmission electron microscopy, Raman spectroscopy and a network analyser. The reflection loss R of less than −20 dB was obtained in the frequency range 3.2–18 GHz. A minimum reflection loss of −43.5 dB was reached at 9.6 GHz with an absorber thickness of 3.1 mm. The in-depth study of relative complex permittivity and permeability reveals that the excellent microwave absorption properties are a consequence of a proper EM match in microstructure, a strong natural resonance, as well as multi-polarization mechanisms, etc.

[1]  V. Bregar,et al.  Advantages of ferromagnetic nanoparticle composites in microwave absorbers , 2004, IEEE Transactions on Magnetics.

[2]  A. Wadhawan,et al.  Nanoparticle-assisted microwave absorption by single-wall carbon nanotubes , 2003 .

[3]  I. Alexandrou,et al.  Fabrication of inorganic molybdenum disulfide fullerenes by arc in water , 2003 .

[4]  X. Zhao,et al.  Characterization of ultrafine γ-Fe(C), α-Fe(C) and Fe3C particles synthesized by arc-discharge in methane , 1998 .

[5]  Yang Liu,et al.  Microwave absorption properties of the carbon-coated nickel nanocapsules , 2006 .

[6]  I. Alexandrou,et al.  Characterisation of carbon nano-onions using Raman spectroscopy , 2003 .

[7]  A. Aharoni.  Effect of surface anisotropy on the exchange resonance modes , 1997 .

[8]  V. P. Shilov,et al.  Ferromagnetic resonance in ferrite nanoparticles with uniaxial surface anisotropy , 1999 .

[9]  O. Acher,et al.  Magnetic resonance in spherical Co-Ni and Fe-Co-Ni particles , 2000 .

[10]  Dimitrov,et al.  Magnetic properties of spherical fcc clusters with radial surface anisotropy. , 1995, Physical review. B, Condensed matter.

[11]  ‡. A. X. Sun,et al.  Microstructure and Magnetic Properties of Fe(C) and Fe(O) Nanoparticles , 2002 .

[12]  J. L. Snoek.  Dispersion and absorption in magnetic ferrites at frequencies above one Mc/s , 1948 .

[13]  Hiroyasu Ota,et al.  GHz microwave absorption of a fine α-Fe structure produced by the disproportionation of Sm2Fe17 in hydrogen , 2002 .

[14]  Chunyi Zhi,et al.  Fabrication and microwave absorption of carbon nanotubes/CoFe2O4 spinel nanocomposite , 2006 .

[15]  P. Watts,et al.  The complex permittivity of multi-walled carbon nanotube–polystyrene composite films in X-band , 2003 .

[16]  O. Acher,et al.  MONODISPERSE FERROMAGNETIC PARTICLES FOR MICROWAVE APPLICATIONS , 1998 .

[17]  J. Robertson.  Diamond-like amorphous carbon , 2002 .

[18]  S. Linderoth,et al.  Surface effects in metallic iron nanoparticles. , 1994, Physical review letters.

[19]  C. Kittel.  On the Theory of Ferromagnetic Resonance Absorption , 1948 .

[20]  J. Charlier,et al.  Defects in carbon nanotubes. , 2002, Accounts of chemical research.

[21]  Keiichi Yamamoto,et al.  Electron energy-loss spectroscopy of carbon onions , 1999 .

[22]  C. Dong,et al.  Electromagnetic wave absorption properties of carbon powder from catalysed carbon black in X and Ku bands , 2006 .

[23]  M. Fujii,et al.  Structure and electronic properties of carbon onions , 2001 .

[24]  Masahiro Itoh,et al.  Electromagnetic wave absorption properties of α-Fe/Fe3B/Y2O3 nanocomposites in gigahertz range , 2003 .

[25]  Jiurong Liu,et al.  Complex permittivity, permeability and electromagnetic wave absorption of α-Fe/C(amorphous) and Fe2B/C(amorphous) nanocomposites , 2004 .

[26]  Masahiro Itoh,et al.  Magnetic and electromagnetic wave absorption properties of α-Fe∕Z-type Ba-ferrite nanocomposites , 2006 .

[27]  Qing Chen,et al.  Microwave Absorption Enhancement and Complex Permittivity and Permeability of Fe Encapsulated within Carbon Nanotubes , 2004 .

[28]  P. Watts,et al.  High Permittivity from Defective Multiwalled Carbon Nanotubes in the X‐Band , 2003 .

[29]  D. Chung,et al.  Flexible graphite under repeated compression studied by electrical resistance measurements , 2001 .

[30]  S. Ramo,et al.  Fields and Waves in Communication Electronics , 1966 .