Origin of large intrinsic flexoelectric coefficients near curie temperature of BaTiO3

Abstract Large effective flexoelectric coefficients have been experimentally obtained near the Curie temperature of many ferroelectric materials, which could greatly accelerate applications of flexoelectricity on actuators and sensors. However, it is still unclear why ferroelectric materials exhibit largest flexoelectric coefficient near their Curie temperatures. Here we employ a modified phenomenological Landau theory to estimate the intrinsic flexoelectric coefficient of BaTiO3 near Curie temperature. It is found that the intrinsic flexoelectric coefficients is largest and reach 1.3 μC/m at TC of its paraelectric phase. The large intrinsic flexoelectric coefficient of paraelectric BaTiO3 is found to correlate with the strong lattice instability of paraelectric phase near TC. This work could help unravel the origin of the large flexoelectric coefficients near TC of ferroelectric materials and would stimulate new research interest into designing ferroelectric materials with high flexoelectric coefficients utilizing phase transitions.