Engineering domain configurations for enhanced piezoelectricity in barium titanate single crystals

In this letter, we propose a mechanism for enhanced piezoelectricity that takes advantage of both intrinsic crystalline anisotropy of ferroelectric crystal and extrinsic 90° domain switching of ferroelectric variant. The domain configurations we consider here are not clamped, and thus allow domain switching driven by the competition between external electric field and internal depolarization field. The intrinsic and extrinsic piezoelectric responses of barium titanate single crystals under different crystallographic orientations are calculated using an energy minimization theory, where it is observed that the piezoelectric coefficient is significantly enhanced by the 90° domain switching, especially under the small field measurement where the domain wall movement is reversible, which is consistent with recent experimental observations. The optimal crystallographic orientation is also identified.