Optimized strain performance in <001>-textured Bi0.5Na0.5TiO3-based ceramics with ergodic relaxor state and core-shell microstructure

Herein, a high strain of similar to 0.3% with a small hysteresis of 43% is achieved at a low electric field of 4 kV/mm in the highly <001>-textured 0.97(0.76Bi(0.5)Na(0.5)TiO(3)-0.24 SrTiO3)-0.03NaNbO(3) (BNT-ST-0.03NN) ceramics with an ergodic relaxor (ER) state, leading to a large normalized strain (d(33)* ) of 720 pm/V. The introduction of NN templates into BNT-ST induces the grain orientation growth and enhances the ergodicity. The highly <001>-textured BNT-ST-0.03NN ceramics display a pure ergodic relaxor state with coexisted ferroelectric R (3) over barc and antiferroelectric P4bm polar nanoregions (PNRs) on nanoscale. Moreover, due to the incomplete interdiffusion between the NN template and BNT-ST matrix, the textured ceramics present a core-shell structure with the antiferroelectric NN core, and thus the BNT-based matrix owns more R (3) over barc PNRs relative to the homogeneous nontextured samples. The high <001> crystallographic texture and more R (3) over barc PNRs both facilitate the relaxor-to-ferroelectric transition, leading to the low-field-driven high strain, while the ergodic relaxor state ensures a small hysteresis. Furthermore, the d(33)* value remains high up to 518 pm/V at 100 degrees C with an ultra-low hysteresis of 6%.