Enhanced piezoelectric properties and thermal stability of LiNbO3-modified PNN–PZT ceramics

Piezoelectric PZT ceramics with high piezoelectric properties and good thermal stability are urgently desired concerning the practical application. New compositions of LiNbO3 modified Pb(Ni1/3Nb2/3)O3PbZrO3PbTiO3 ceramics have been prepared in this study. The effects of the introduction of the LiNbO3 on the system were comprehensively investigated in terms of the phase structure, microstructure, electric properties, and thermal stability behavior of the ceramics. All compositions are located in the morphotropic phase boundary (MPB) region, and the ratio of the rhombohedral (R) phase increases obviously with the increase of LiNbO3 concentration. With increasing the LiNbO3 content, the piezoelectric properties were significantly enhanced. The sample added with 2 % (in mole) LiNbO3 shows excellent electric properties, including Tm = 185 °C, εr = 5,643, kp = 0.626, Qm = 51, d33 = 902 pC/N. More importantly, no thermal depolarization behavior was observed in the temperature range of 25∼100 °C. For PNN-PZT-xLN ceramics, which is mainly attributed to the pinning effect resulted by the (LiPb′−NbB−site∙) defect dipoles.