Flexoelectric Effect of Ferroelectric Materials and Its Applications

Abstract

The flexoelectric effect, which exists in all dielectrics, is an electromechanical effect that arises due to the coupling of strain gradients (or electric field gradients) with electric polarization (or mechanical stress). Numerous experimental studies have demonstrated that ferroelectric materials possess a larger flexoelectric coefficient than other dielectric materials; thus, the flexoelectric response becomes significant. In this review, we will first summarize the measurement methods and magnitudes of the flexoelectric coefficients of ferroelectric materials. Theoretical studies of the flexoelectric coefficients of ferroelectric materials will be addressed in this review. The scaling effect, where the flexoelectric effect dramatically increases when reducing the material dimension, will also be discussed. Because of their large electromechanical response and scaling effect, ferroelectric materials offer vast potential for the application of the flexoelectric effect in various physical phenomena, including sensors, actuators, and transducers. Finally, this review will briefly discuss some perspectives on the flexoelectric effect and address some pressing questions that need to be considered to further develop this phenomenon.