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