Flexoelectricity of barium titanate

Flexoelectricity was investigated as a function of temperature in paraelectric and ferroelectric phases of barium titanate ceramic. The flexoelectric coefficient μ12 was measured dynamically at small level of strain gradients. μ12 is around 5μC∕m in orthorhombic phase, rises to about 10μC∕m at room temperature, and peaks at ∼50μC∕m near tetragonal-cubic phase transition point. The coupling effect between mechanical strain gradient and electric polarization is found to be nonlinearly enhanced by high dielectric permittivity and domain contribution in barium titanate. In inhomogeneously strained ferroelectrics, mechanical gradient field may impact electric polarization in a way analogous to electric field.