Significant effects of minor chemical composition changes on the structure and property of (Pb1−ySry)(Mg1/3Nb2/3)0.07ZrxTi0.93−xO3:zLa

Abstract

Piezoelectric ceramics with high electrical performances and high Curie temperature (T_c) act as key materials for numerous electromechanical devices such as transducers and actuators. Herein, we report a systematic investigation on the crystal structure, microstructure and electrical properties of Sr and La co-doped Pb(Mg_1/3Nb_2/3)O₃–PbZrO₃–PbTiO₃ ceramics with a low Pb(Mg_1/3Nb_2/3)O₃ content, namely, (Pb_1−ySr_y)(Mg_1/3Nb_2/3)_0.07Zr_xTi_0.93−xO₃:zLa. With an increase in the Zr content (x value) from 0.49 to 0.53, its crystal structure evolved from a tetragonal phase to a rhombohedral phase, leading to not only a morphotropic phase boundary (MPB) at around x = 0.51 but also a monotonously decreasing T_c. Meanwhile, a change in either the Sr- or La-doping content (y and z values, respectively) in the range of y = 0.03–0.07 and z = 0.01–0.03 can slightly deviate the structure of MPB, resulting in a significant effect on its electrical properties. As the best results, the optimal composition of x = 0.51, y = 0.05, and z = 0.02 yielded peak electrical performance, with a related room temperature piezoelectric coefficient (d₃₃) of 645 pC N⁻¹, remanent polarization (P_r) of 33.5 μC cm⁻², coercive field (E_c) of 8.6 kV cm⁻¹, and T_c of 242 °C. Especially, its piezoelectric properties showed excellent temperature stability, and its d₃₃ value decreased by only 3% from room temperature to 150 °C. This work not only provides an alternative piezoelectric ceramic with outstanding electrical performance for industrial applications, but also reveals a comprehensive perspective on the composition–structure–property relationship of doped Pb[(Mg_1/3Nb_2/3),Zr,Ti]O₃, which is helpful for further work on piezoelectric ceramics.