Composition-dependent phase evolution and enhanced electrostrain properties of (Bi0.5Na0.5)TiO3-BaTiO3-Bi(Li0.5Ta0.5)O3 lead-free ceramics

B.V Exploring lead-free materials to substitute the commercialized PZT-based compounds is in great demand for the development of miniaturized and nonhazardous actuator devices. Here, a new ternary lead-free (1-x)(Bi0.5Na0.5)(1-y)BayTiO3-xBi(Li0.5Ta0.5)O-3 (BNBTy-xBLT) solid solution system is designed to optimize the electrostrain performance of the well-studied BNT ceramics, and the effects of BLT and Ba substitutions on phase evolution as well as electrical performances of BNT ceramics are systematically investigated. All the compositions prepared by solid-state sintering process exhibit similar pseudocubic phase with rhombohedral/tetragonal distortions in nanoregions. Through optimizing the BLT and Ba contents, the composition with 6.9 mol% Ba and 0.8 mol% BLT exhibits the maximum unipolar strain of similar to 0.39% (equivalent normalized strain d(33)*similar to 654 pm/V, 60 kV/cm). Moreover, the origin of the excellent electrostrain response is emphatically analyzed from microscopic (domain structure evolution) and macroscopic (TF-R shifting) perspectives, which results from the electric-field-induced reversible relaxor-ferroelectric phase transition. These results suggest the composition-optimized BNT-BT-BLT system as a potential alternate to lead-based systems in actuator applications. (C) 2019 Elsevier B.V. All rights reserved.