High and temperature-insensitive piezoelectric performance in the lead-free Sm-doped BiFeO3–BaTiO3 ceramics with high Curie temperature

Large sensor piezoelectric constant (d₃₃ = 334 pC/N) and superior actuator piezoelectric constant (d₃₃* = 552 pm/V) as well as a high Curie temperature (T_C = 454 °C) were obtained simultaneously in the lead-free 0.67Bi_1.03FeO₃-0.33Ba_1-xSm_xTiO₃ ceramics. Such an excellent and temperature-insensitive piezoelectric performance with only 10% temperature variation of piezoelectric strain at the range of 25–125 °C is highly desirable for real applications. The structural origin of the enhanced piezoelectric performance is mainly attributed to the morphotropic phase boundary and the highest known tetragonality (c_T/a_T = 1.02) in such materials. Transmission electron microscopy and electro-mechanical phenomenological theory demonstrate that the superior d₃₃ and d₃₃* are associated with the hybrids nanodomains (60–90 nm) and flattened thermodynamic energy profile owing to the local structure heterogeneity. These results are superior as the piezoelectric properties are temperature-independent and the material has large d₃₃*, and high T_C compared to other lead-free piezoelectric ceramics.     

The structural origin of enhanced energy harvesting performance in piezoelectric perovskite

Energy harvesting, which can translate the wasted vibration energy into electric energy, is now a hot topic in the field of new energy, and the key point is to design high power piezoelectric ceramic according with the requirements of low-frequency vibration energy harvesting. In this study, high quality Co-modified 0.2Pb(Zn_1/3Nb_2/3)O₃–0·8Pb(Zr_0·50Ti_0·50)O₃ (PZN–PZT+Co) ceramics have been prepared by the two-stage method, and the energy harvesting characteristics were investigated. The results showed that the hierarchical nanodomain structure boosts the strong piezoelectric activity, leading to the high energy harvesting performance. The PZN–PZT+Co ceramic sintered at 1000 °C exhibits an excellent d₃₃ × g₃₃ value of 14080 × 10^?15 m²/N, which are much larger than that of commercial PZT-based ceramics. In the mode of the cantilever-type energy harvester, the output voltage and energy density of 33 V, 4.4 μW/mm³ were obtained at a low resonance frequency of 85 Hz and acceleration of 10 m/s², showing potential application in piezoelectric energy harvester.