Giant piezoelectric response in piezoelectric/dielectric superlattices due to flexoelectric effect

Flexoelectricity describes the linear response of electricalpolarization to a strain gradient, which can be used to enhance thepiezoelectric effect ofpiezoelectric material or realize thepiezoelectric effect in nonpiezoelectric materials. Here, we demonstrate from thermodynamics theory that a giantpiezoelectric effect exists in piezoelectric/dielectricsuperlattices due toflexoelectric effect. The apparentpiezoelectric coefficient is calculated from the closed-form of analytical expression of thepolarization distribution in the piezoelectric/dielectricsuperlattice subjected to a normal stress, in which theflexoelectric effect is included. It is found that there exists a strong nonlinear coupling between theflexoelectric andpiezoelectric effects, which significantly enhances the apparentpiezoelectric coefficient in the piezoelectric/dielectricsuperlattice. For a specific thickness ratio of thepiezoelectric and dielectric layers, the enhanced apparentpiezoelectric coefficient in thesuperlattice is ten times larger than that of its purepiezoelectric counterpart. The present work suggests an effective way to obtain giant apparentpiezoelectric effect in piezoelectric/dielectricsuperlattices throughflexoelectric effect.

Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Chang Liu, Huaping Wu and Jie Wang Source Type: research