Mélanges à fort contraste diélectrique et milieux effectifs : une théorie étendue

International audienceBruggeman's formula for the effective dielectric permittivity of a binary metal-insulator composite shows in thress dimensions a permittivity transition for a critical value fc=1/3 of the metal volume fraction. We present a method that allows one to correct this threshold in a perturbative way, accounting for the statistics assumed for the problem. This method originates in a renormalization for both the polarizabilities and the dipolar Green function. It leads to a modification of Bruggeman's formula. Associated numerical results are reported in the low-frequency limit. The paper ends with experimental results, analyzed in the context of this approach