High Piezoelectricity in Eco-Friendly NaNbO₃-Based Ferroelectric Relaxor Ceramics via Phase and Domain Engineering

To meet the requirements of environmental friendliness, high-performance lead-free piezoelectric materials have become important materials for next-generation electronic devices. Here, lead-free and potassium-free NaNbO 3 (NN)-based ceramics with high piezoelectric ( d 33 = 361 ± 10 pC/N) and dielectric (ε r = 4500) properties were obtained by tolerant preparation techniques. The excellent piezoelectric and dielectric properties can be attributed to the relaxor morphotropic phase boundaries (R–MPB) and coexisting domain regions, which are beneficial in lowering the free energy and greatly improving the dielectric response and domain switching capability. Furthermore, the d 33 of NaNbO 3 -10Ba(Ti 0.7 Sn 0.3 )O 3 -1.5NaSbO 3 (NN-10BTS-1.5NS) ceramics can be maintained at 350 pC/N over the range of 25–80 °C with a change rate of less than 10%, exhibiting excellent temperature stability. Based on a series of in situ characterizations, the variations of the phase and domain structures of NN-based relaxor piezoelectric ceramics with temperature are clearly demonstrated. This work not only proposes new materials for sensors and actuators but also provides an excellent strategy for designing high-performance piezoelectric ceramics through phase and domain engineering.