Enhanced piezoelectric and electric field induced stain response in Bi0.5Na0.5TiO3–Ba(Zr0.055Ti0.945)O3 ceramics modified by (K0.5Na0.5)NbO3

Abstract

Due to people pay more attention to environmental protection, lead-free piezoelectric ceramics have become the focus of contemporary research. In this paper, a new ternary (0.93−x)Bi0.5Na0.5TiO3–0.07Ba(Zr0.055Ti0.945)O3–x(K0.5Na0.5)NbO3 (BNT–BZT–xKNN) (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07) solid solution were synthesized by two-step solid-state reaction method. The variations of ferroelectric, piezoelectric and electric field induced strain properties with composition were investigated. It is found that KNN substitution induces a ferroelectric to relaxor phase transition. The x = 0.01 sample dominated by ferroelectric phase shows improved d33 of 180 pC/N. The x = 0.02 sample with coexistence of the ergodic and nonergodic relaxor exhibits large unipolar strain of ~ 0.31% with low strain hysteresis of ~ 33.5% and the corresponding large signal d33* is ~ 476 pm/V. For the ceramics with x = 0.07, the ergodic relaxor is dominant, which shows the unipolar stain of ~ 0.27% under 90 kV/cm, accompanied by strain hysteresis of ~ 16.3%. From 30 to 150 °C, under the electric field of 60 kV/cm, the change of strain is ~ 25.8% and ~ 17.6% for 0.02 KNN and 0.07 KNN ceramics, respectively. Our results indicate BNT–BZT–xKNN ceramics with different KNN content are promising candidates for sensor and actuator applications.