Flexoelectricity in Ferroelectrics: From Fundamentals to Applications
Flexoelectricity, the generation of electrical polarization in response to a strain gradient, is a fundamental electromechanical coupling mechanism that has gained significant attention due to its enhanced effects in ferroelectric materials, which exhibit large dielectric permittivities. This review comprehensively examines the classical theories and recent advances in flexoelectricity, with a primary focus on ferroelectric materials. We discuss the advantages and limitations of various characterization techniques, computational models for determining flexoelectric coefficients, and the mechanisms that enhance flexoelectricity in different ferroelectric systems. Furthermore, we explore the applications of flexoelectricity in devices, highlighting its potential to overcome the dimensional and stability limitations of piezoelectricity, particularly at the micro- and nanoscale. The review concludes by outlining future research directions, aiming to provide valuable insights for advancing both the fundamental science of flexoelectricity and the development of high-performance practical devices.