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Bismuth sodium titanate (BNT)‐based lead‐free piezoceramics are promising for replacing lead‐based piezoceramics in piezoelectric actuators due to their large strains. However, achieving low‐hysteresis large‐strain BNT‐based ceramics over a broad temperature range is challenging, owing to the complexity of the composition design and phase transformation. Herein, a lead‐free relaxor‐ferroelectric (1−x)Bi0.47Na0.47Ba0.06TiO3‐xK0.47Na0.47Li0.06Nb0.99Sb0.01O2.99 system (BNBT‐KNLNS) near the morphotropic phase boundary (MPB), achieved by phase‐field simulations and rational composition design (i.e., BNBT with the MPB as the base and the ferroelectric phase of KNLNS as the dopant) is reported. This ceramic exhibits large strains (0.32–0.51%) and low strain hysteresis (11.1–59.9%) over a wide temperature range (25–125 °C), outperforming many state‐of‐the‐art lead‐free piezoceramics. A small fraction of ferroelectric states embedded in the relaxor matrix is experimentally observed, where these states act as seeds, facilitating the reversible relaxor‐to‐ferroelectric transition. In addition, the MPB composition with low energy barriers yields large strain responses, owing to the easy polarization reversal and extension. Consequently, low‐hysteresis large strains are obtained over a broad temperature range. This work provides a novel design route for discovering high‐performance piezoceramics for actuator applications. [ABSTRACT FROM AUTHOR]

One of the key problems in the existing lead‐free piezoelectrics lies in how to further boost their dynamic piezoelectric responses, i.e., electrostrain and dynamic piezoelectric constants, in an effective and facile manner, making them comparable to those of widely used lead‐based counterparts. In this work, a new strategy is developed to largely improve the dynamic piezoelectric properties of lead‐free ferroelectrics using phase field simulations by combining the relaxor/ferroelectric crossover rendering potentially reversible electrostrain and the morphotropic phase boundary (MPB) providing easy paths of ferroelectric polarization rotations. Following the guidance of simulation results, Mn‐doped (Bi0.5Na0.5)TiO3–BaTiO3 lead‐free piezoelectric ceramics with relaxor/MPB crossover are synthesized. A large reversible electrostrain (Smax) of 0.55% with a promising piezoelectric constant d33* (Smax/Emax) of 917 pm V–1 at the designed relaxor/MPB crossover is obtained, outperforming almost all practical lead‐free counterparts when taking both electrostrain and dynamic piezoelectric constants into consideration. The strategy of utilizing relaxor/MPB crossover provides a new route for enhancing the dynamic piezoelectric responses in lead‐free ferroelectric perovskites. [ABSTRACT FROM AUTHOR]

Keywords: lead-free piezoceramics; morphotropic phase boundaries; phase-field simulations; piezoresponse force microscopy; strain EN lead-free piezoceramics morphotropic phase boundaries phase-field simulations piezoresponse force microscopy strain 1 1 1 08/11/22 20220808 NES 220808 B Lead-Free Piezoceramics b In article number 2202307, Linglong Li, Dong Wang, and Xiaojie Lou, and co-workers report a computationally aided composition design for discovering high-performance lead-free perovskite piezomaterials. Lead-free piezoceramics, morphotropic phase boundaries, phase-field simulations, piezoresponse force microscopy, strain The obtained bismuth sodium titanate-based relaxor-ferroelectric ceramic demonstrates low-hysteresis large strains over a wide range of temperatures, which holds great promise for practical applications of actuator devices operating at room to high temperatures. [Extracted from the article]