Dielectric media based on isolated metallic nanostructures

We study the dielectric properties of nanocomposites in the 0-1.5-GHz frequency regime. These composites consist of electrically insulated metallic nanoparticles and carbon nanotubes, the elongated nanostructures in this study, uniformly dispersed in a dielectric matrix. We find that the properties of these composites depend crucially on the shape and monodispersity of the nanoparticles. While at high concentrations the spherical nanoparticles cause only slight modification of the dielectric function of the composite with respect to the matrix, the elongated nanoparticles produce composites with an enhanced real part of the dielectric function and low imaginary part. Our theory, which is in excellent agreement with these results, suggests specific ways to further improve the dielectric properties of the composites. (c) 2005 American Institute of Physics.