Temperature-insensitive large strain response with a low hysteresis behavior in BNT-based ceramics

Abstract

A ternary solid solution Ba(Zr0.05Ti0.95)O3-modified (Bi0.5Na0.5)TiO3–(Bi0.5K0.5)TiO3 (BNT–BKT–BZT) was designed and prepared by solid state synthesis. The phase stability and macroscopic electromechanical properties were systematically investigated with an emphasis on the relationship between the structure evolution and strain behavior, and a schematic phase diagram is proposed. Increasing the content of BZT decreased the ferroelectric-to-relaxor phase transition temperature TF-R and induced the reversible transition from the relaxor pseudocubic to ferroelectric rhombohedral phase, giving rise to a promising strain behavior at a critical composition x=0.02 featured by not only high electric-induced normalized strain of Smax/Emax=503pm/V but also a relatively small hysteresis compared with existing BNT-based lead-free ceramics. In particular, by limiting the electric driving field to exclude the contribution from the converse piezoelectric effect, a temperature-insensitive Smax/Emax was obtained in the investigated temperature range from room temperature to 120°C. Furthermore, a high electrostrictive coefficient (Q11) of 0.0237 m4C−2 was achieved at room temperature for the composition with 10mol% BZT, that was highly stable within the investigated temperature and electric field ranges.