LIU Kang ¹, LAN Zhencheng ¹, CHEN Kaiyuan ¹, WAGN Hui ², YU Qiang ³, LIU Laijun ¹

(1. College of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, Guangxi, China; 2. Yuchai Engineering Research Institute, Guangxi Yuchai Machinery Co, Ltd, Nanning 530000, Guangxi, China; 3. National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China)

Abstract: High temperature piezoelectric ceramics have important applications in fuel injection systems, diesel engine shock absorption and spacecraft performance monitoring. In this paper, (1-x)BiScO₃-xPbTiO₃(x=0.60-0.66) high temperature piezoelectric ceramics near the morphotropic phase boundary (MPB) were prepared by using the conventional solid-state method. Rietveld refinement was used to determine the coexistence of monoclinic and tetragonal phases, while the relationship between the atomic position and the ratio of the two phases to the composition was elucidated. By identifying the coupling between the two dynamic isopotential states which increased the polarizability, the mechanism the enhancement in piezoelectric and ferroelectric properties of this component range was clarified. The BS-PT (x=0.64) ceramics have the best room temperature piezoelectric and ferroelectric properties, with T_c=430 °C, d₃₃=450 pC/N, k_p=62%, P_r =38 µC/cm² and E_c=22.7 kV/cm. The d₃₃ remains unchanged after thermal annealing until 370 °C and decreases sharply at 410 °C, which is higher than that of the ordinary PZT ceramics by 220 °C. Therefore, they are potential candidates as high-temperature piezoelectric ceramics.
Key words: BiScO₃-PbTiO₃; piezoelectric ceramics; MPB; thermal stability