Excellent piezoelectric constant and thermal stability in BiScO₃–PbTiO₃ piezoelectric ceramics via domain engineering

The application of piezoelectric ceramics at high temperature is limited because they can't have both high piezoelectric coefficient and high Curie temperature. While, BiScO₃–PbTiO₃-based piezoelectric ceramics possessing high Curie temperature and piezoelectric properties simultaneously have drawn increasing attention due to their potential applications at high temperature. Here, we reported a novel compositional design of (1-x)[0.36BiScO₃-0.64PbTiO₃]-xBi(Sn_1/3Nb_2/3)O₃ (abbreviated as BS-PT-xBSN). BS-PT-xBSN ceramic samples were synthesized by conventional solid state reaction method. According to the ternary phase diagram of BS-PT-xBSN ceramics brought up in this work, the morphotropic phase boundaries (MPB) were confirmed, which is located in the vicinity of x = 0.02. It canbe identified that the x = 0.02 sample near MPB has the optimal electric performance which are giant piezoelectric coefficient (d₃₃ ~ 450 pC/N, higher 18 % than undoped samples) and high Curie temperature (T_c ~ 368 ℃) as well as large remant polarization (P_r ~ 46.6 μC/cm²). In addition, the variation of P_r is 3 % in the temperature range of 30–180 ℃ and the depolarization temperature of x = 0.02 ceramics is about 280 ℃. Structural analysis such as in-situ PFM and TEM confirms that giant piezoelectricity and depolarization temperature are attributed to the appearance of nano-domain and complexity of domains as well as the stable domain configuration. This work not only reveal the high potential of BS-PT-xBSN for high-temperature piezoelectric applications but also open up a feasible approach to design new high-temperature piezoelectric ceramics.