Significant effects of minor chemical composition changes on the structure and property of (PbSr)(MgNb)ZrTiO:La.

Piezoelectric ceramics with high electrical performances and high Curie temperature () 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(MgNb)O-PbZrO-PbTiO ceramics with a low Pb(MgNb)O content, namely, (PbSr)(MgNb)ZrTiO:La. With an increase in the Zr content ( 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 = 0.51 but also a monotonously decreasing . Meanwhile, a change in either the Sr- or La-doping content ( and values, respectively) in the range of = 0.03-0.07 and = 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 = 0.51, = 0.05, and = 0.02 yielded peak electrical performance, with a related room temperature piezoelectric coefficient () of 645 pC N, remanent polarization () of 33.5 μC cm, coercive field () of 8.6 kV cm, and of 242 °C. Especially, its piezoelectric properties showed excellent temperature stability, and its 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[(MgNb),Zr,Ti]O, which is helpful for further work on piezoelectric ceramics.