Design of superior electrostriction in BaTiO₃‐based lead‐free relaxors via the formation of polarization nanoclusters

Abstract Electrostrictive materials have wide applications in modern high‐precision electronic devices. Driven by growing environmental concerns, there is demand for lead‐free materials with superior electrostriction behaviors. In this study, we demonstrate a record‐high electrostrictive coefficient of ~0.0712 m⁴ C⁻² in perovskite ferroelectric ceramics, along with hysteresis‐free strain as well as excellent frequency and thermal stabilities, in lead‐free BaTiO₃‐based ceramics through a polarization nanocluster design. By appropriately introducing Li⁺ and Bi³⁺ into the BaTiO₃ lattice matrix, the long‐range ferroelectric ordering can be broken, and polarization nanoclusters can be formed, resulting in a relaxor state with concurrently suppressed polarization and maintained electro‐strain. A three‐dimensional atomic model constructed using advanced neutron total‐scattering data combined with the reverse Monte Carlo method indicates the existence of Bi and Li segregations at the subnanometer scale, which confirms the prediction made by density functional theory calculations. Such a short‐range chemical order destroys the long‐range ferroelectric order of the off‐centered Ti polar displacements and leads to the embedding of Li⁺/Bi³⁺‐rich polar nanoregions in the Ba²⁺‐rich polarization disorder matrix. Further, a completely reversible electric‐field‐induced lattice strain is observed, giving rise to pure electrostriction without hysteresis behavior. This work provides a novel strategy for developing lead‐free relaxor ferroelectrics with high electrostriction performance. image