Extremely High Piezoelectric Properties in Pb-Based Ceramics through Integrating Phase Boundary and Defect Engineering.

An ultrahigh piezoelectric coefficient is always desired for electromechanical devices and systems. However, for a long time, a large d33 value in lead-based and lead-free piezoelectric ceramics was usually obtained at the expense of their Tc, and vice versa, limiting their practical applications. Here, we proposed a design concept, i.e., integrating phase boundary and defect engineering, to resolve the above challenges, based on a concrete example of Fe-modified 0.51Pb(Hf0.35Ti0.65)O3-0.49Pb(Nb2/3Ni1/3)O3 (0.51PHT-0.49PNN) ceramics. An abnormally high d33 value of 1124 pC/N and a Tc of 133 °C were achieved simultaneously in this study, which are obviously superior to those of other reported representative lead-based and lead-free piezoelectric ceramics, which made a giant step forward in both piezoelectric material research and electromechanical applications. A large strain response of 0.28% and low hysteresis were also obtained under an applied field of 20 kV/cm in the 0.51PHT-0.49PNN ceramic. The phase-field simulations and piezoresponse force microscopy demonstrated that the high piezoelectric performance should be attributed to the formation of mesoscopic domains resulting from morphotropic phase boundary and defect dipoles. Most importantly, this work provides an avenue for the development of piezoelectric ceramics with ultrahigh d33 and high Tc and has the potential to lead to the development of a range of high-performance Pb-based ceramics for electromechanical applications in the future.