High dielectric loss in graphite-coated Ti nanocapsules

Graphite-coated Ti nanocapsules, with Ti nanoparticles as core and onion-like graphite layers as shell, have been prepared by a modified arc-discharge method in ethanol atmosphere, and characterized by means of X-ray diffraction, transmission electron microscopy and Raman spectroscopy. The dielectric properties of the graphite-coated Ti nanocapsules have been investigated in the 2-18 GHz range. An equivalent circuit model was used to interpret the non-linear dielectric resonance behavior of the graphite-coated Ti nanocapsules. The high dielectric loss is mainly attributed to conductance loss and dipole-relaxation loss in the graphite-coated Ti nanocapsules. The graphite-coated Ti nanocapsules exhibit promising properties for application as a new type of shield or absorbent of electromagnetic waves.