Abstract: Bismuth layer-structured ferroelectrics (BLSFs) are promising candidates for high-temperature piezoelectric sensors materials due to their high Curie temperatures, which enable stable charge signal output under elevated temperature conditions. However, the low piezoelectric activity of pure Bi₄Ti₃O₁₂ (BIT) limits its practical applications. In this study, we aim to enhance the piezoelectric performance of BIT ceramics through A/B-site co-doping. A series of Bi_4-xCe_xTi_2.98Cr_0.02O₁₂ (BCTC-100x, x = 0-0.015) ceramics were synthesized via a conventional solid-state reaction method. The microstructure and electrical properties were systematically characterized. The results demonstrate that Ce/Cr co-doping induces orthorhombic lattice distortion, reduces oxygen vacancy concentration, and promotes preferential orientation of polarization vectors along the a-axis after poling. The optimized BCTC-1.0 composition exhibits an enhanced piezoelectric constant d₃₃ of 19.5 pC/N, a high Curie temperature T_C of 659 ℃, and a maximum polarization P_max of 12.6 μC/cm². Notably, the piezoelectric constant d₃₃ retains approximately 84% of its room-temperature value after annealing at 600 ℃, demonstrating excellent thermal stability. These findings indicate that Ce/Cr co-doping is an effective strategy for synergistically enhancing the piezoelectric response and high-temperature stability of BIT-based ceramics. This work provides a feasible pathway for developing high-performance piezoelectric materials for high-temperature sensor applications.

Key words: Bi₄Ti₃O₁₂, Ce/Cr co-doping, piezoelectric properties, lattice distortion