Two-step synthesized method strategy of long-range ordered and relaxor ferroelectrics achieves excellent electrical performance and thermal stability in BF-BT based Ceramics

Abstract

Achieving high piezoelectric performance in BiFeO₃-BaTiO₃-based ceramics while enhancing the stability of the piezoelectric coefficient (d₃₃) during depolarization presents a significant challenge. Their poor thermal stability stems from intrinsic defects and the disruption of long-range ferroelectric order induced by the doping of foreign elements. This study employs a two-step synthesized method strategy, combining long-range-ordered ferroelectrics with relaxor ferroelectrics. By modifying the domain structure characteristics, the energy barrier for switching polar structures is increased, thereby achieving enhanced thermal stability. This process yields high d₃₃ (93 pC/N) and high depolarization temperature (T_d ~ 650 ℃), while effectively mitigating the continuous decline in d₃₃ observed in relaxor ferroelectrics from room temperature to Td. After depolarization at 650 ℃ for 3 hours, the variation in d₃₃ (Δd₃₃/d₃₃) is only 17.2%. Furthermore, the resistivity (ρ) remains as high as 1.3 × 10⁶ Ω·cm at 300 ℃. Furthermore, ultrasonic experiments based on this piezoelectric material confirmed that at 300 ℃, the symmetric (S₀) and antisymmetric (A₀) zero-order modes maintained high signal-to-noise ratios of 21.6 dB and 20.3 dB, respectively. These results highlight the strong potential of the ceramic for high-temperature ultrasonic structural health monitoring (SHM) systems.