Tunability and loss of the ferroelectric-dielectric composites

This paper addresses the modeling of dielectric-dielectric composites, consisting of an electrically tunable (nonlinear) dielectric mixed with a linear, low loss dielectric. Different models of the redistribution of components in the composite have been considered to evaluate its electrical properties. The effective dielectric permittivity, effective tunability and effective loss tangent of the columnar, layered, and spherical inclusions composites have been modeled using exact analytical solutions and a solution based on the effective medium approximation (EMA). A finite element method (FEM) analysis has been used to estimate the tunability of the composite at strong nonlinearities (large signal regime). It is shown that in the case of ferroelectric-dielectric composite the addition of small amounts of the linear dielectric into the tunable ferroelectrics leads to a small increase of the tunability of the mixture. At the same time, the loss tangent of the composite is virtually unaffected by the addition of the low-loss dielectrics.