Large Strain Response in <001> Textured 0.79BNT–0.20BKT–0.01NKN Lead‐Free Piezoelectric Ceramics

Abstract

Templated grain growth (TGG) method was applied to fabricate textured lead‐free piezoelectric ceramics 0.79Bi0.5Na0.5TiO3–0.20Bi0.5K0.5TiO3–0.01Na0.5K0.5NbO3 (0.79BNT–0.20BKT–0.01NKN) using plate‐like Bi4Ti3O12 (BiT) grains, to improve its performances. Relationships between degree of orientation, microstructure, and piezoelectric properties of the textured ceramics were studied. Results showed that dense, c‐axis (00l) textured 0.79BNT–0.20BKT–0.01NKN ceramics, with brick wall cross‐sectional microstructures and strip‐like grains aligned parallel to the tape casting direction, were obtained using this method. The highest degree of orientation (Lotgering factor f = 94%) was achieved in samples with template content of 20 wt%. However, these samples did not exhibit enhanced strain response due to the composition deviation induced by the interdiffusion of BiT into the matrix composition. Instead, maximum strain value of 0.45% was observed in the textured sample with 5 wt% template, which was 50% higher than that of random ceramics and comparable with some PZT‐based anti‐ferroelectric ceramics, suggesting the textured ceramics could be a very promising lead‐free piezoelectric material for application in electromechanical devices.