Defect Dipole Asymmetry Response Induces Electrobending Deformation in Thin Piezoceramics

Ultrahigh electrostrains (>1%) in several piezoceramic systems have been reported since 2022, which attracts more and more interest in the field of piezoelectricity; however, the mechanism is still unclear. Here, in nonstoichiometric (K_{0.48}Na_{0.52})_{0.99}NbO_{2.995} ceramics, we have directly observed a novel electric field-induced bending (electrobending) phenomenon that visually exhibits an alternating concave-convex deformation under an electric field of ±50  kV cm^{-1}, leading to the measured ultrahigh electrostrain. It is demonstrated that the electrobending deformation arises from the different stresses due to the stretching or compression of the oriented-defect dipoles in the upper and lower surface layers of the ceramics under an electric field. Consequently, a giant apparent electrostrain of 31.8% is obtained at room temperature. Our discovery is an important addition and refinement to the field of condensed matter physics, while also providing a new strategy and shedding light on the design of future high-performance actuators and intelligent devices.