Flexoelectric charge separation and size dependent piezoelectricity in dielectric solids

Flexoelectric charge separation and the associated size dependent piezoelectricity are investigated in centrosymmetric dielectric solids. Direct piezoelectricity can exist as external mechanical stress is applied to non-piezoelectric dielectrics with shapes such as truncated pyramids, due to elastic strain gradient induced flexoelectric polarization. Effective piezoelectric coefficient is analyzed in truncated pyramids, which is strongly enhanced by size reduction and depends on flexoelectricity, elastic compliance, and aspect ratio of the non-piezoelectric dielectric solids.