Dielectric response and tunability of a dielectric-paraelectric composite

Abstract

A theoretical study was carried out to determine the dielectric response and tunability of a composite consisting of a linear, low-loss dielectric matrix with uniformly sized, randomly distributed paraelectric Ba0.60Sr0.40TiO3 (BST 60/40) particles as functions of the volume fraction and size of the particles. The field dependence of the polarization and the dielectric response of the inclusions are specified through a nonlinear thermodynamic model and then incorporated into a two-dimensional finite element analysis. Near the percolation threshold for BST particles (similar to 27% to 45% depending on the particle size), high dielectric tunabilities with a lower effective permittivity than monolithic BST can be realized. (C) 2008 American Institute of Physics. American Institute of Physics.