On Flexoelectricity in a Multidomain Ferroelectric

Flexoelectricity in a macroscopically unpolarized multidomain ferroelectric is considered. It has been shown that the flexoelectric moduli are modified due to the piezoelectric effect in individual domains. The perturbation theory has been developed, where the effect appears in the third order. The estimate of the effect for lead titanate in the isotropic approximation has shown that corrections to the flexoelectric moduli f₁₁₁₁ and f₁₁₂₂ are comparable with their initial values and depend only on the initial value of f₁₂₁₂. The correction to f₁₂₁₂ is small, which allows one to use the perturbation theory.