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

The effects of crystallographic texture and microstructure are analyzed for polycrystalline tetragonal BaTiO₃, pseudotetragonal PZN–PT, and cubic BaTiO₃. For tetragonal BaTiO₃ and pseudotetragonal PZN–PT, we demonstrate that a high anisotropy of the single-crystal properties induces an apparent enhancement in the macroscopic piezoelectric response. For tetragonal BaTiO₃, the predicted macroscopic piezoelectric constants d ₃₁ and d ₃₃ are enhanced with respect to its single-crystal value at the expense of the spatial contributions from d ₁₅. For samples possessing fiber texture, an optimal response is predicted for samples that are not perfectly textured. Similarly, an apparent enhancement of the macroscopic value of d ₁₅ is predicted for PZN–PT. For cubic BaTiO₃, the low anisotropy of the underlying crystal properties induces a uniform decrease of the macroscopic electrostrictive constant, Q ₁₁, with decreasing texture. A completely random polycrystal provides 0.85±0.05 times its single-crystal response.