Microwave absorption properties of the carbon-coated nickel nanocapsules

The carbon-coated Ni(C) nanocapsules were prepared by a modified arc-discharge method in methane atmosphere. Its electromagnetic parameters were measured at 2-18 GHz. It is observed that the natural resonance which appeared at 5.5 GHz is dominant among microwave absorption properties of Ni(C) nanocapsules, as the consequence of the increased surface anisotropic energy for nanosized particles. The measured relative complex permittivity indicates that a high resistivity existed in Ni(C) nanocapsules samples. The maximum reflection loss of Ni(C) nanocomposites can reach 32 dB at 13 GHz with 2 mm in thickness. The microwave absorptive mechanisms of Ni(C) nanocapsule absorbent were discussed.