Piezoelectricity

Physics

Bent molecular geometry

Nanotechnology

Shrinkage

Flexoelectricity

Nanoscopic scale

Crystallography

Bending

Perovskite (structure)

Dielectric

Nanoelectromechanical systems

Physical chemistry

Nanomedicine

Nanoparticle

Composite material

Flexural strength

Chemistry

Materials science

Deformation (meteorology)

Polarization (electrochemistry)

Condensed matter physics

Optoelectronics

Ferroelectricity

Nature Communications

Recent realizations of ultrathin freestanding perovskite oxides offer a unique platform to probe novel properties in two-dimensional oxides. Here, we observe a giant flexoelectric response in freestanding BiFeO 3 and SrTiO 3 in their bent state arising from strain gradients up to 3.5 × 10 7 m −1 , suggesting a promising approach for realizing ultra-large polarizations. Additionally, a substantial change in membrane thickness is discovered in bent freestanding BiFeO 3 , which implies an unusual bending-expansion/shrinkage effect in the ferroelectric membrane that has never been seen before in crystalline materials. Our theoretical model reveals that this unprecedented flexural deformation within the membrane is attributable to a flexoelectricity–piezoelectricity interplay. The finding unveils intriguing nanoscale electromechanical properties and provides guidance for their practical applications in flexible nanoelectromechanical systems.

Enhanced polarization and abnormal flexural deformation in bent freestanding perovskite oxides