Effective permittivity of composites with stratified particles

The effective electromagnetic, thermal and mechanical properties of heterog eneous media are commonly related to composition. Stratified composites are entities that are important in physics and engineering and are a class of compounds actively investigated for their dielectric properties. Such syste ms consist of composite inclusions of multicomponent materials embedded in a matrix of a distinct material. The effects of the volume fraction, permit tivity and thickness of the various constituents on the complex effective p ermittivity of the heterostructures, in the quasistatic approximation, are reported, We use an exact numerical technique for the evaluation of the die lectric characteristics of three-component composites, arranged in a regula r simple cubic lattice, which is based on the field calculation package PHI 3D and a boundary integral equations solution scheme of Laplace's equation. 'Exact' means that the correct properties are computed for the given micro structure and choice of individual component properties because all interna l electric multipole interactions contributing to the polarization of the m aterial medium are taken into account. The predictions of the Steeman and M aurer (dipolar) theory (Steeman P A M and Maurer F H J 1992 Colloid Polym. Sci. 270 1069) are compared with our numerical results where appropriate. A n important feature, suggested by the results presented for stratified sphe res and spheroids, is that any approach based solely on the dipole approxim ation must fail to predict the effective permittivity of dielectric heteros tructures over the entire range of volume fraction of inclusions. The resul ts discussed give motivation for the development of careful experiments whi ch can be used to test the numerical simulations and to fabricate synthetic composite materials in which new electromagnetic properties can be obtaine d from the combination of several materials.