The Effect of Texture and Microstructure on the Macroscopic Properties of Polycrystalline Piezoelectrics: Application to Barium

The effects of crystallographic texture and microstructure are analyzed for polycrystalline tetragonal BaTiO3, pseudotetrago-nal PZN–PT, and cubic BaTiO3. For tetragonal BaTiO3 and pseudotetragonal PZN–PT, we demonstrate that a high anisot-ropy of the single-crystal properties induces an apparent en-hancement in the macroscopic piezoelectric response. For tetragonal BaTiO3, the predicted macroscopic piezoelectric con-stants d31 and d33 are enhanced with respect to its single-crystal value at the expense of the spatial contributions from d15. For samples possessing fiber texture, an optimal response is predict-ed for samples that are not perfectly textured. Similarly, an apparent enhancement of the macroscopic value of d15 is pre-dicted for PZN–PT. For cubic BaTiO3, the low anisotropy of the underlying crystal properties induces a uniform decrease of the macroscopic electrostrictive constant, Q11, with decreasing texture. A completely random polycrystal provides 0.8570.05 times its single-crystal response. I