Abstract: Abstract High-piezoelectric properties in lead-free materials have been the pursuit for both industry and scientific research. In this work, the synergistic approaches of phase/domain engineering and novel poling method are adopted for the improvement of piezoelectric performance. The strategically designed lead-free donor-doped BiFeO₃-xBaTiO₃ ceramics at the crystal structure morphotropic phase boundary (MPB) between the rhombohedral and tetragonal phases exhibited a high Curie temperature (T_C ≥ 450 °C). Furthermore, simultaneously enhanced static piezoelectric constant (d₃₃) of 436± 5 pC/N and thermally stable dynamic piezoelectric constant (d₃₃*) of 550± 10 pm/V were achieved. The high piezoelectric performance is collectively attributed to the crystal structure MPB, thermal quenching effect, local structure heterogeneity induced by donor doping, mesoscale nanodomains, and novel poling method inside a magnetic field. The temperature-insensitive and high piezoelectric performance of the current work is superior to the other lead-free piezoceramics. The synergistic approach for the improvement of piezoelectricity provides a path for the development of lead-free ceramics for high-temperature commercial applications.

Key words: Lead-free piezoceramics, BiFeO₃-BaTiO₃, Quenching, Temperature-insensitive, AC-poling