EFFECT OF DISORDER ON THE FREQUENCY-DEPENDENT DIELECTRIC-CONSTANT OF A COMPOSITE-MATERIAL

We evaluate, by an analytic-simulation method, the frequency-dependent dielectric constant e() of a composite material consisting of spherical inclusions with a frequency-dependent dielectric constant 1(), distributed with varying degrees of randomness, in a matrix characterized by a frequency-independent dielectric constant 2. The form of 1() is given by a Drude model, as would be appropriate for metallic inclusions. We have previously applied the method to liquidlike disorder [Kumar and Cukier, J. Phys. Chem. 93, 4334 (1989)]. Here we consider disordered lattices, vacancy lattices, size-distributed liquids, and a more realistic Drude function appropriate to silver in a glass matrix. We find that the line shape Ime() is broadened by the allowance for the electrostatic interactions among the inclusions in comparison with the Maxwell-Garnett prediction. The degree of broadening depends on the kind and amount of disorder. The method is more efficient than the customary lattice-sum approach, which utilizes Ewald sums, and yields results in close agreement with the latter. © 1990 The American Physical Society.