title: Composition- and temperature-driven phase transition characteristics and associated electromechanical properties in Bi0.5Na0.5TiO3-based lead-free ceramics.
abstract: In this study, a lead-free ceramic system comprising (0.94 - x)Bi0.5Na0.5TiO3-0.06BaTiO3-xBi(Zn0.5Ti0.5)O3 (BNT-BT-BZT) was designed and prepared by a conventional solid-state reaction method. The effect of the addition of BZT on the phase transition characteristics and associated electromechanical properties of BNT-BT was systematically discussed and a schematic phase diagram was established. The addition of BZT had a strong impact on the phase transition as well as the strain and piezoelectric activity. The phase coexistence, which involves ferroelectric rhombohedral-relaxor pseudocubic phases, can be driven by modification with BZT and increases in temperature and can be confirmed by XRD measurements, analysis of Raman spectra and temperature-dependent changes in polarization and strain hysteresis loops. Accompanied by a shift in the ferroelectric-to-relaxor temperature TF-R to below room temperature on the addition of BZT, a compositionally induced ferroelectric-to-relaxor phase transition occurred, which gave rise to a large strain of 0.33% with a normalized strain Smax/Emax of 550 pm V(-1) at the critical BZT content x of 0.0275. The results were closely correlated with the composition and dependence on temperature of the phase transition, which significantly influenced the electromechanical properties, and the origin of the large strain observed in the present system was also addressed in detail. As a result, the design principles provided in this study open the possibility of obtaining BNT-based lead-free ceramics with enhanced electromechanical properties for actuator applications.
authors.affiliation: College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310018, China.
authors.forename: Wangfeng
authors.initials: W
authors.lastname: Bai
authors.affiliation: College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310018, China.
authors.forename: Daqin
authors.initials: D
authors.lastname: Chen
authors.affiliation: College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310018, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zheng
authors.affiliation: Functional Materials Research Laboratory, School of Materials Science & Engineering, Tongji University, No. 4800 Caoan Highway, Shanghai 201804, China. apzhai@tongji.edu.cn.
authors.forename: Bo
authors.initials: B
authors.lastname: Shen
authors.affiliation: Functional Materials Research Laboratory, School of Materials Science & Engineering, Tongji University, No. 4800 Caoan Highway, Shanghai 201804, China. apzhai@tongji.edu.cn.
authors.forename: Jiwei
authors.initials: J
authors.lastname: Zhai
authors.affiliation: College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310018, China.
authors.forename: Zhenguo
authors.initials: Z
authors.lastname: Ji