Grain Plastic Rearrangement for Fabricating Textured CaBi₂Nb₂O₉-Based Ceramics with Superior Piezoelectricity

Bismuth layer-structured ferroelectrics (BLSFs) play an important role in high-temperature piezoelectric applications due to their high Curie temperature (T_C) and excellent fatigue-resistant performance, while they have long faced the problem of insufficient piezoelectric properties. The phenomenological orientational average theory demonstrates that the [100]-oriented CaBi₂N₂O₉ (CBN) ceramics can improve d₃₃ of conventional ceramics by 77% via utilizing their strong in-plane piezoelectric response. Building on this finding, a seed-free hot forging technique is proposed to fabricate [100]-oriented textured CBN-based ceramics via grain plastic rearrangement at high temperatures. This method yields a textured CBN-based ceramic with a superior d₃₃ of 26.7 pC/N, which is 53% higher than the standard ones. Remarkably, the d₃₃ of textured CBN-based ceramics remains at 25.7 pC/N even after annealing at 900 °C. Our seed-free hot forging technique, which eliminates the need for grain templates, is significantly simpler than traditional template grain growth methods and holds significant potential for application across various BLSF ceramics. This work presents a cost-effective and straightforward approach to producing high-performance textured BLSF ceramics, marking a significant step forward in the development of high-temperature piezoelectric applications.