Effective-medium theory of dielectric-constant anomalies in ferroelectric composites

Abstract The effective-medium approximation is applied to find the temperature dependence of the components of the dielectric tensor for three main forms of embedded-ferroelectric composite: layers (superlattice), cylinders and spheres. Divergences in one or more component occur at the critical temperature, either for all concentrations or when the ferroelectric concentration is above a percolation threshold. The results are illustrated with numerical values of the parameters for a typical perovskite ferroelectric.