High temperature 0.63BiFeO₃-0.37BaTiO₃ based ceramics with large electromechanical properties by simple A-site K⁺ doping

Designing high temperature piezoelectric ceramics with large electromechanical properties is key to the actuators application in harsh environment. BiFeO₃-BaTiO₃ based piezoelectric ceramics are the promising candidates due to their high electromechanical properties and high Curie temperature. Here, the simple A-site single K⁺ doped 0.63Bi_1−xK_xFeO₃-0.37BaTiO₃ (abbreviated as 0.63B_1−xK_xF-0.37BT) ceramics with positive temperature dependent electromechanical properties were fabricated via conventional solid phase method. The electromechanical properties in the 0.63B_1−xK_xF-0.37BT ceramics are closely related to the content of K⁺ doping. The excellent electromechanical properties of S= 0.26% and d₃₃*=861 pm/V under low electric field of 30 kV/cm at 105 ℃ are achieved in the 0.63B_0.9975K_0.0025F-0.37BT ceramic, which is conducive to their application at high temperature. Combined with the microstructure and PFM, the optimized electromechanical properties in 0.63B_0.9975K_0.0025F-0.37BT ceramic are mainly due to more nanodomains switching facilitated by the large grain size and local structural heterogeneity. The site engineering of A-site single ion doping is an efficient and simple strategy for BF-BT based piezoelectric ceramics to achieving excellent electromechanical properties under low electric field at high temperature.