NaNbO3 templates-induced phase evolution and enhancement of electromechanical properties in <001> grain oriented lead-free BNT-based piezoelectric materials

Recently developed Bi0.5Na0.5TiO3(BNT)-based piezoceramics face two urgent obstacles: high driving field required to trigger large strain and poor temperature stability. Highly oriented (1-x)(0.83Bi(0.5)Na(0.5)TiO(3)-0.17Bi(0.5)K(0.5)TiO(3))-xNaNbO(3) (BNT-BKF-xNN) piezoceramics were synthesized using NN templates to resolve both obstacles. Measurements of polarization and strain hysteresis loops as well as phase transition temperature revealed a phase evolution from ergodic relaxor to ferroelectric phases, generating a high strain of 0.43% and large S-max/E-max=720pm/V for textured BNT-BKT-4NN ceramics. The field dependent strain was largely depended on the degree of texturing. Most intriguingly, grain-oriented specimens provided excellent actuating performance characterized by both large S-max/E-max = 693 pm/V at a low driving field of 45 kV/cm and enhanced temperature stability with S-max/E-max = 537pm/V at 120 degrees C. This was basically ascribed to the facilitated switching between ergodic relaxor and ferroelectric phases owing to the grain-oriented structure. As a consequence, design of < 001 > oriented microstructure opens the possibility to produce efficient BNT-based piezoceramics for transferral into real-world applications. (C) 2017 Elsevier Ltd. All rights reserved.