Optimal electromagnetic-wave absorption by enhanced dipole polarization in Ni/C nanocapsules.

Electromagnetic-wave (EMW) absorption by Ni/C nanocapsules with similar permeability but different permittivity mainly due to differences in the graphite-shell thickness has been investigated. The optimal working frequency could appear at S-band and C-band and considerable strong EMW absorption was achieved. For the optimal Ni/C nanocapsules, a reflection loss exceeding -20 dB was reached from 2.6 to 8.2 GHz with a maximum value of -40 dB at 3 GHz. The improved absorption can be attributed to an optimal electromagnetic match and an enhanced dipole polarization upon increasing of shell thickness. [ABSTRACT FROM AUTHOR]