Grain-boundary and crack effects on the dielectric response of high-permittivity films and ceramics

Abstract

Grain-boundary and crack effects on the dielectric response of high-permittivity films and ceramics were analyzed using the generalized effective-medium approximation. It was demonstrated that the brick-wall and coated spheres models, which become equivalent for a small porosity, best describe the strong reduction of the dielectric response and hardening of the soft-mode frequency recently revealed in SrTiO3 films and PbZrO3 ceramics.