Lutetium‐substituted high-TC Bi5Ti3FeO15 exhibiting superior piezoelectric performance

Due to industrial and technological advancements, there is a growing demand for piezoelectric ceramics that can operate at high temperatures. Bismuth layer-structured ferroelectric (BLSF) bismuth titanate-ferrite (Bi 5 Ti 3 FeO 15 ) has attracted significant attention because of its high Curie temperature ( T C ) of 763 °C. However, research on the piezoelectric performance of Bi 5 Ti 3 FeO 15 is limited due to its poor piezoelectric properties and low direct-current (dc) electrical resistivity at elevated temperatures. In this study, we propose optimizing the composition of Bi 5 Ti 3 FeO 15 ceramics by partially substituting bismuth (Bi 3+ ) ions with lutetium (Lu 3+ ) ions to improve their piezoelectric performance and dc electrical resistivity. We thoroughly investigate the structural, ferroelectric, dielectric, and piezoelectric properties of lutetium-substituted Bi 5 Ti 3 FeO 15 (BTF-100 x Lu). The results indicate that the optimal composition, BTF-4Lu, exhibits excellent piezoelectric performance with a piezoelectric constant ( d 33 ) of 23.0 pC/N, which is more than three times that of Bi 5 Ti 3 FeO 15 (7.1 pC/N). Additionally, BTF-4Lu demonstrates a high dc electrical resistivity of 1.6 × 10 7 Ω cm at 300 °C and a T C of 771 °C. Moreover, the thermal annealing behavior of the piezoelectric performance and the temperature-dependent electrical impedance and resonance frequencies demonstrate the excellent thermal stability of the piezoelectric properties of lutetium-substituted Bi 5 Ti 3 FeO 15 ceramics.