Synergistic Phase Boundary and Defect Engineering Enables Ultrahigh Electrostrain in Lead‐Free Ceramics
Xinru Nie, Ruiyi Jing, Fukang Chen, Leiyang Zhang, Yule Yang, Zupei Yang, Shirui Zhang, Huan Jiao, Haibo Zhang, Haibo Yang, Li Jin
Abstract
Abstract Piezoelectric ceramics serve as essential materials for electromechanical transduction; however, they face two critical limitations: the environmental toxicity associated with conventional lead‐based systems and the inadequate strain performance, typically below 0.5%, observes in current lead‐free alternatives. In this work, a synergistic design approach is presented to address both challenges by simultaneously modulating the room‐temperature nonergodic relaxor to ergodic relaxor phase boundary and introducing engineered defect dipoles ( P d ) in (Bi 0.5 Na 0.5 ) 0.93 Ba 0.07 TiO 3 (BNBT) ceramics through B‐site co‐substitution with aliovalent (Sn 0.5 Sb 0.4 ) 4+ complex ions. This dual‐modulation strategy leverages field‐induced phase transitions, the morphotropic phase boundary effect, and the cooperative alignment between spontaneous polarization and defect dipole polarization. As a result, the material system exhibits markedly suppressed negative strain, a substantial internal bias field that facilitates reversible domain switching, and an exceptional electromechanical response. Specifically, an ultrahigh electrostrain of 1.06%, a giant effective piezoelectric coefficient of 1317 pm V −1 , and an ultralow strain hysteresis of 7.2% are achieved. These metrics rival those of benchmark lead‐based ceramics such as Pb(Zr 1‐ x Ti x )O 3 . The proposed methodology offers a promising pathway for the development of high‐performance, environmentally benign actuator materials suitable for advanced electromechanical applications.