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

Yves-Patrick Pellegrini (1) , Jérôme Pommier (1) , Jean-Jacques Niez (1)

1 CESTA - Centre d'études scientifiques et techniques d'Aquitaine

Bruggeman'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.

Mots clés: Random dielectric media; effective-medium theory; perfect disorder; diagrammatic expansion; percolation threshold

Domaines: Systèmes désordonnés et réseaux de neurones [cond-mat.dis-nn]

Yves-Patrick Pellegrini, Jérôme Pommier, Jean-Jacques Niez. Mélanges à fort contraste diélectrique et milieux effectifs : une théorie étendue. Comptes-Rendus de l'Académie des Sciences, Série 2, 1993, 316, pp.305-309. ⟨cea-00413018⟩