Effect of Microstructure and Texture on the Macroscopic Piezoelectric Response of Ferroelectric Barium Titanate and PZN—PT Films

Abstract

A two-dimensional (2D) plane-strain finite element method (FEM) model of polycrystalline film wherein the film thickness is much greater than the microstructure is presented. A finite element based solution for the rigorous homogenization problem to quantify the microstructural features, such as orientation and spatial distribution of crystallographic grains on the global piezoelectric response of unclamped polycrystalline ferroelectric films is implemented. The homogenized material parameters of the piezoelectric films are calculated using the FEM by the solution of the coupled equilibrium electrical and mechanical fields in the linear domain. The dependence of macroscopic electromechanical properties on domain orientation and texture of single-crystalline as well as polycrystalline ferroelectric BaTiO3 and PZN—PT films are demonstrated based on this model. The orientation dependent anisotropy of homogenized electromechanical moduli of polycrystalline and single-crystalline films are examined. The polycrystalline films can be improved in their out-of-plane global piezoelectric behavior by engineering microstructures that favor {111} texture in the case of BaTiO3 and {001} texture in the case of PZN—PT.