3D-Simulation of Topology-Induced Changes of Effective Permeability and Permittivity in Composite Materials

We have performed 3D simulations of complex effective permittivityand permeability for random binary mixtures of cubic particles belowthe percolation threshold. We compare two topological classes that correspond to different spatial particle arrangements: cermet topology and aggregate topology. At a low filling factor of f=10%, where most particles are surrounded by matrix material, the respective effective materialparameters are indistinguishable. At higher concentrations, a systematicdifference emerges: cermet topology is characterized by lower effectivepermittivity and permeability values. A distinction between topologicalclasses might thus be a useful concept for the analysis of real systems,especially in cases where no exact effective-medium model is available