Tailoring electromechanical performance in BiScO3-modified Bi0.5Na0.5TiO3-based lead-free piezoceramics

The strain response of lead-free ternary solid solution (1 - x) (0.94 Bi0.5Na0.5TiO3-0.06BaTiO(3))-xBiScO(3) (BNT-BT-BS) have been tailored by controlling the phase transition temperature. The effects of BiScO3 on the phase structure, dielectric, ferroelectric, piezoelectric properties, and electric field-induced strain are systematically investigated. A schematic phase diagram has also been established to clarify the relationship between strain behavior and structure evolution. The field-induced strain increases progressively, and a large strain of 0.35% with S-max/E-max = 471 pm/V is achieved at the critical composition x = 0.03, owing to the shift of the ferroelectric-to-relaxor transition temperature TF-R to ambient temperature. Intriguingly, the established correlation between strain response and TF-R demonstrates that the optimization of strain behavior of BNT-based ceramics can be realized though the regulation of TF-R to room temperature. Furthermore, a high and thermally stable electrostrictive coefficient Q(33) of 0.018 m(4)/C-2 can also be attained at the composition x = 0.06. In this study, it is believed that the modulation of phase transition temperature is feasible to achieve the large strain response in BNT-based ceramics.