Abstract:The flexoelectric effect in solid dielectrics refers to the elastic strain gradient generated electric polarization, or the elastic deformation induced by an electric field strain. Since the strain gradient can locally break the inversion symmetry of materials, the flexoelectric effect is a universal electromechanical coupling effect in solid dielectrics. The flexoelectric effect is inversely proportional to the scale of materials due to the strain gradient and electric field gradient, therefore, it becomes significant or even dominant the overall physical properties of materials at the nanoscale. Compared with piezoelectric effect and electrostrictive effect, the flexoelectric effect has the unique size effect characteristics. Moreover, the flexoelectric effect is not limited by the symmetry of materials and Curie phase transition temperature of ferroelectric materials. This work reviewed the flexoelectric effect in solid dielectrics, especially on the theoretical and experimental understanding of it in solid dielectrics. In addition, a perspective on the future directions of the flexoelectric effect in solid dielectrics is provided to discuss the flexoelectric effect in materials.