Concurrently enhanced piezoelectric performance and curie temperature in stressed lead-free Ba<sub>0.85</sub>Ca<sub>0.15</sub>Ti<sub>0.9</sub>Zr<sub>0.1</sub>O<sub>3</sub> ceramics.

Su, Yuanhui; Wang, Qingying; Huan, Yu; Wang, Jianli; Sun, Wei; Li, Yongjun; Wei, Tao; Cheng, Zhenxiang · Nat Commun · 2025

basic_science · Level V

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Abstract

Eco-friendly, lead-free BaTiO<sub>3</sub>-based piezoelectrics are critical for sustainable electronics, but improving their piezoelectric properties often compromises Curie temperature (T<sub>C</sub>). To address this trade-off, we implemented an innovative stress engineering approach by introducing a secondary phase BaAl<sub>2</sub>O<sub>4</sub> in Ba<sub>0.85</sub>Ca<sub>0.15</sub>Ti<sub>0.9</sub>Zr<sub>0.1</sub>O<sub>3</sub> (BCTZ) ceramics. The thermal expansion mismatch between BCTZ and BaAl<sub>2</sub>O<sub>4</sub> induces internal stress within the BCTZ matrix, causing significant lattice distortion and phase fraction modulation, which improves both T<sub>C</sub> and the piezoelectric coefficient (d<sub>33</sub>). Additionally, the local electric field and Al<sup>3+</sup> doping in ABO<sub>3</sub> lattice further enhance d<sub>33</sub>. Optimized BCTZ ceramics achieve d<sub>33</sub> of 650 ± 16 pC N<sup>-1</sup>, d<sub>33</sub><sup>*</sup> of 1070 pm V<sup>-1</sup>, and T<sub>C</sub> of 96.5 ± 1.0 °C, placing them at the forefront of lead-free BaTiO<sub>3</sub>-based piezoelectrics. This study underscores the effectiveness of bulk stress engineering via a secondary phase for enhancing lead-free piezoelectric ceramics, paving the way for developing high-performance piezoelectric ceramics suitable for broad temperature applications.