Template Reinforcement Enables Highly Textured Lead-Free BiFeO₃-Based Piezoceramics With Exceptional Performance

Lead-free BF-based piezoelectric ceramics are attracting much interest in high-temperature piezoelectric systems owing to their high Curie temperature (T_c) and good thermal stability. However, their development toward integration in piezoelectric devices has been severely impeded by unsatisfied overall properties. Herein, a template reinforcement texture process was proposed to fabricate highly textured BF-based piezoceramics with exceptional performance. The plate-like BaTiO₃ templates undergoes annealing treatment to enhance mechanical properties, enabling them to maintain shape integrity and function normally as seed crystals. Consequently, the resultant lead-free BF-based textured piezoelectric ceramics exhibit ultrahigh texture degree (F₀₀₁ = 97.0%) and exceptional piezoelectric performance (d₃₃ = 303 ± 10 pC/N, T_c = 512°C, k_p = 43.4%). Multiscale structural analysis and phase-field simulation revealed that enhanced piezoelectric performance could be attributed to the large lattice distortion, formed engineered "4R" and "1T" domains configuration, precisely controlled rhombohedral/tetragonal (R/T) phase ratio, and induced nanodomain structures with decreased domain wall energy. Moreover, the piezoelectric circular diaphragm prepared based on the texture ceramic exhibits excellent energy harvesting performance in the temperature range of 25°C-250°C. Therefore, this work provides a novel and effective method for enhancing the comprehensive piezoelectric performance of lead-free BF-based ceramics.