BiFeO₃–BaTiO₃ (BF–BT) ceramics exhibit higher piezoelectric coefficients (d₃₃), Curie temperatures (T_C), and temperature stability than other high-temperature lead-free piezoelectric materials. However, despite their crucial role in piezoelectric devices, the mechanical properties of BF–BT ceramics have been underexplored. A thorough evaluation of the mechanical properties of BF–BT is crucial for developing cost-effective and durable lead-free piezoelectric ceramics. Moreover, the specific causes of the high piezoelectric response and excellent temperature stability of BF–BT ceramics remain unclear owing to the instrumental detection threshold, which limits experimental studies to temperatures above 140 °C and below the degradation temperature of d₃₃. To investigate the intrinsic origins of the high piezoelectricity and temperature stability of BF–xBT ceramics and to enhance their mechanical properties, a two-step sintering process is used to fabricate these ceramics (0.25 ≤ x ≤ 0.40). Owing to improvements in grain refinement and reduced Bi³⁺ volatilization, the BF–0.33BT ceramic exhibits enhanced overall performance, with a modified small punch strength of 155 MPa, Vickers hardness of 5.2 GPa, a d₃₃ of 220 pC/N at room temperature, T_C of 466 °C, and d₃₃ values exceeding 400 pC/N at 260 °C. Phase-field simulations, which address the limitations of device detection thresholds, reveal that with increasing temperature, the domain structure relaxes, and polarization intensity decreases. This indicates that changes in the high-temperature piezoelectric properties can be attributed to domain structure relaxation and the increase in dielectric constant. Overall, BF–BT ceramics exhibit superior piezoelectric performance, mechanical properties, and temperature stability, making them highly suitable for use in high-temperature and demanding environments.

中文翻译：

---

具有增强温度稳定性和机械性能的高压电无铅 BiFeO3–BaTiO3 陶瓷


与其他高温无铅压电材料相比，BiFeO 3-BaTiO₃ （BF-BT） 陶瓷表现出更高的压电系数 （d₃₃）、居里温度 （T_C） 和温度稳定性。然而，尽管它们在压电器件中起着至关重要的作用，但 BF-BT 陶瓷的机械性能尚未得到充分探索。对 BF-BT 的机械性能进行全面评估对于开发经济高效且耐用的无铅压电陶瓷至关重要。此外，由于仪器检测阈值，BF-BT 陶瓷高压电响应和优异温度稳定性的具体原因尚不清楚，这限制了实验研究在 140 °C 以上和低于 d₃₃ 降解温度的温度。为了研究 BF-xBT 陶瓷高压电性和温度稳定性的内在起源并提高其机械性能，使用两步烧结工艺 （0.25 ≤ x ≤ 0.40） 来制造这些陶瓷。由于晶粒细化的改善和Bi³⁺挥发的减少，BF-0.33BT陶瓷表现出增强的整体性能，改性后的小冲头强度为155 MPa，维氏硬度为5.2 GPa，室温下 d₃₃ 为 220 pC/N，T _C 为 466 °C，d₃₃260 °C 时值超过 400 pC/N。 解决器件检测阈值局限性的相场仿真表明，随着温度的升高，畴结构松弛，极化强度降低。 这表明高温压电性能的变化可以归因于磁畴结构松弛和介电常数的增加。总体而言，BF-BT 陶瓷表现出卓越的压电性能、机械性能和温度稳定性，使其非常适合在高温和苛刻的环境中使用。