Theoretical investigation of the nanoinclusions shape impact on the capacitance of a nanocomposite capacitor

Abstract

A first-principles theoretical approach to the effective dielectric permittivity of a nanocomposite, which contains nanoinclusions dispersed in a host dielectric enclosed between two parallel metallic electrodes, is developed. The inclusions are modeled by spheroids, and their response to the external electric field is found using the point dipole approximation and Green’s function approach. As a result, besides the mutual interactions between the induced dipoles, the local field in the nanocomposite contains also a contribution from the dipole field reflected from the capacitor electrodes. It is shown that the nanocomposite dielectric permittivity is determined by an average inclusion polarizability density, and its dependence on the aspect ratio and orientations of inclusions is found analytically and investigated. The theoretical predictions derived in the paper are in excellent agreement with the available experimental data and can be used for a proper design of nanocomposite capacitors.