Giant Electrobending with Superior Thermal Stability in (K,Na)NbO ₃ Based Lead‐Free Piezoceramics: Insights from Polarization Configuration

ABSTRACT

Electrobending in lead‐free piezoceramics has recently achieved remarkable attention, but the intrinsic coupling between electrobending and polarization configuration remains inadequately understood —leading to temperature instability that plagues practical applications. Herein, combining finite element analysis, density functional theory calculations, phase‐field simulations, in situ property measurements and atomic‐scale scanning transmission electron microscopy (STEM), we revealed that polarization configuration with enhanced switchability can promote inconsistent transverse shrinkage between the upper and lower surfaces of ceramics under an external electric field and leads to enhanced electrobending. By designing multiscale flexible polarization configuration, we achieved a giant apparent unipolar electrostrain (S _uni ∼2.2%, d ₃₃ ^* ∼11 000 pm/V @ 2 kV/mm) with exceptional temperature stability (∼10% variation over the range of −40°C–160 °C) in (K,Na)NbO ₃ ‐based ceramics, which outperforms the state‐of‐the‐art lead‐free piezoceramics. In addition, this ceramic also exhibits excellent comprehensive piezoelectric properties, with a small‐signal d ₃₃ of ∼500 pC/N and T _c of ∼240°C. This study advances the understanding of electrobending, which could provide valuable insights for the rational design of next‐generation lead‐free piezoceramics with excellent comprehensive performances.