Ultrahigh piezoelectricity of PNN–PZT ceramics via constructing defect dipoles

The ultrahigh piezoelectric coefficient (d33 ≥ 1000 pC/N) exhibited by piezoelectric Pb(Zr,Ti)O3 (PZT) ceramics not only captivates researchers but also holds considerable practical value across various applications. While significant progress has been made in enhancing piezoelectricity of PZT-based ceramics, novel mechanisms need to be proposed to explain the piezoelectric behavior of new systems with ultrahigh d33. In this study, we initially employ LiNbO3 as an additive to enhance the piezoelectric properties of the Pb(Ni1/3Nb2/3)O3–PbZrO3–PbTiO3 ceramics. and the optimal performance is achieved by incorporating 1.5 mol% of LiNbO3 into the system, resulting in an ultrahigh d33∼1178 pC/N (d33* ∼1560 pm/V (@ E = 5 kV/cm)). The corresponding mechanism for this superior piezoelectric response involves the AB-site co-doping effect, especially the (LiPb′−NbZr/Ti∙) defect dipoles formed by the introduction of LiNbO3. In particular, the addition of LiNbO3 leads to a more uniform distribution of domain sizes, thereby further enhancing the ultrahigh piezoelectricity. These findings pave the way for a deeper under-standing of the origin of ultrahigh piezoelectric properties and make substantial contributions to the advancement of piezoelectric materials for practical applications in electromechanical devices.