Dramatical improvement in temperature stability of ZnO modified PNN-PZT ceramics via synergistic effect of doping and composite

In this work, doping and composite are simultaneously utilized to improve the Tm of 0.55 Pb(Ni1/3Nb2/3)O3-0.135PbZrO3-0.315PbTiO3 ceramic by adding ZnO (PNN-PZT:xZnO). It is found that Zn ions prefer to substitute for Ni ions, making Ni ions spontaneously crystallize at grain boundaries in the form of an oxide. Moreover, limited by the solid solubility, superfluous ZnO particles also stay at grain boundaries with the increasing ZnO content. Thus, triple contribution of ions substitution, local stress fields and electric fields coexist in the PNN-PZT:xZnO ceramics with high ZnO content, dramatically improving the Tm from 102 °C to 171 °C. The excellent comprehensive electromechanical performance is obtained in the sample with x = 0.05: d33 ∼ 824 pC/N, d33* ∼1059 p.m./V, Tm ∼140 °C, Ec ∼5.2 kV/cm, Qm ∼87. As the ceramic is heated to 125 °C, its k33 and d33 values still remain ∼67% and ∼80% of the corresponding room temperature values as evidenced by in-situ temperature stability measurement. Our results indicate that PNN-PZT:xZnO ceramics are the most promising candidates to develop high-performance medical ultrasound transducers for imaging, meanwhile, provide a fresh design strategy to optimize the performance of the piezoelectric ceramics.