Enhanced Piezoelectricity and Excellent Thermal Stability in Sm3+-Doped BiFeO3-PbTiO3 Ceramics

Piezoelectric ceramics with combined high piezoelectric performance and excellent thermal stability are important and urgently needed for actuation and sensor applications in harsh environments, such as aerospace, automotive, oil, and gas exploration industries. However, the development of such piezoceramics is still a highly challenging task because an enhanced piezoelectric response is generally accompanied by a decrease in thermal stability. Here, we report that 0.55Bi(1-x)Sm(x)FeO(3)-0.45PbTiO(3) piezoceramics exhibit a balanced trade-off between piezoelectric response and thermal stability near the morphotropic phase boundary (MPB), where piezoelectric coefficient d(33) (275 pC N-1) barely changes even at a temperature as high as 320 degrees C and the well-squared shape P-E hysteresis loop persists even at a high temperature of 220 degrees C. Compared with La3+, Sm3+ has a smaller ionic radius than Bi3+ or Pb2+ and thus could be more effectively to induce MPB at a relatively low substitution level (x = 0.16-0.21). In turn, the thermal stability of the piezoceramics does not degrade significantly. Our results further demonstrate that Sm substitution induces a strong relaxor behavior in the ceramics. These results suggest that the Sm3+-doped BiFeO3-PbTiO3 ceramics hold great promise for high temperature piezoelectric applications.