Concurrently enhanced piezoelectric performance and curie temperature in stressed lead-free Ba0.85Ca0.15Ti0.9Zr0.1O3 ceramics

Eco-friendly, lead-free BaTiO3-based piezoelectrics are critical for sustainable electronics, but improving their piezoelectric properties often compromises Curie temperature (TC). To address this trade-off, we implemented an innovative stress engineering approach by introducing a secondary phase BaAl2O4 in Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCTZ) ceramics. The thermal expansion mismatch between BCTZ and BaAl2O4 induces internal stress within the BCTZ matrix, causing significant lattice distortion and phase fraction modulation, which improves both TC and the piezoelectric coefficient (d33). Additionally, the local electric field and Al3+ doping in ABO3 lattice further enhance d33. Optimized BCTZ ceramics achieve d33 of 650 ± 16 pC N−1, d33* of 1070 pm V−1, and TC of 96.5 ± 1.0 °C, placing them at the forefront of lead-free BaTiO3-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. Lead-free piezoelectric ceramics typically face a trade-off between Curie temperature and piezoelectric response. Here, the authors demonstrate a stress engineering via BaAl2O4 incorporation in BaTiO3-based ceramics simultaneously achieves high Curie temperature and piezoelectric response.