Strong piezoelectric anisotropy in CaBi ₄ Ti ₄ O ₁₅ textured ceramics prepared by templated grain growth method

Abstract Bismuth layer‐structured ferroelectrics (BLSF) show great potential as piezoelectric materials for high‐temperature applications. In this study, c ‐axis/[001]‐textured CaBi 4 Ti 4 O 15 (CBT) ceramic was synthesized through templated grain growth (TGG) method. A high Lotgering factor ( f ) of 96% was achieved in textured CBT ceramic using 20 wt% CBT homogeneous template. The piezoelectric coefficient d 33 has significantly increased from 7.8 pC/N for random ceramic to 24.3 pC/N for textured ceramic (poled perpendicular to the c ‐axis/[001] texture direction), representing an impressive 300% enhancement while maintaining an ultra‐high Curie temperature ( T C ) of 788°C. In addition, a low dielectric loss (tan δ = 0.4%) and relatively high resistivity (ρ = 1.1 × 10 12 Ω·cm) were achieved simultaneously at room temperature. The significant enhancement of d 33 in textured CBT ceramic origins from its strong piezoelectric anisotropy. The large d 33,T⊥ is due to the nature of polarization switching in CBT (the spontaneous polarization P S of CBT is along a ‐axis direction, and the switching of P S is restricted within the a – b plane). Furthermore, the variation of d 33,T⊥ remained below 10% across the temperature range of 25–700°C, highlighting the excellent thermal stability of the textured CBT ceramics. These findings suggest that textured CBT ceramic is a promising piezoelectric material for high‐temperature sensor applications.