Superior high-temperature piezoelectric performances in BF-PT-BT ceramics via electric field constructed phase boundary

Owing to the mutual restriction between piezoelectric coefficient ( d ₃₃ ) and Curie temperature ( T _c ), the discovery of high-temperature piezoceramics with large d ₃₃ is highly desirable but challenging. Here, BiFeO ₃-BaTiO ₃-PbTiO ₃ (BF-BT-PT) ternary system is redesigned by combining the low lattice distortion of BF-BT perovskites and rhombohedral-tetragonal coexistence of BF-PT phase boundary. As a result, excellent comprehensive piezoelectric properties with a large d ₃₃ of ∼380 pC/N and a high T _c of ∼483 °C are obtained in a tetragonal composition close to the triple point. Interestingly, even though a c/ a ratio as large as 1.04 can be detected in the virgin sample, hierarchical domains that macrodomains composed of nanosized stripe domains can be found. The tetragonal phase could partly transform into a monoclinic phase under electric field according to in-situ high-energy synchrotron X-ray diffraction measurement, constructing a field-induced morphotropic phase boundary. The large lattice distortion and unstable phase structure simultaneously contribute to the high T _c, and large d ₃₃ for the studied BF-BT-PT ceramics, respectively, showing great potential for high-temperature sensors and transducers.