Percolation in composites

Many properties of composite materials such as diffusion, electrical conduc tion, dielectric response as well as elasticity, are intimately related to the geometrical arrangement of the constitutive phases, including the geome try of the respective interfaces. Percolation theory, whose objective is to characterize the connectivity properties in random geometries and to explo re them with respect to physical processes, thus provides a natural frame f or the theoretical description of random composites. This article explains basic concepts of static percolation theory and percolative transport, whic h subsequently are applied to specific experiments on heterogeneous ionic c onductors.