Role of BO6 octahedral distortion on high temperature piezoelectric properties in Bi_3-x(Li_0.5Sm_0.5)_xTiNbO₉

A series of bismuth layer structured ferroelectrics (BLSFs) Bi_3-x(Li_0.5Sm_0.5)_xTiNbO₉ (abbreviated as BTNO-100xLS, x = 0, 0.01, 0.02, and 0.03) high temperature piezoelectric ceramics were prepared by solid state reaction sintering. The microstructure, piezoelectric properties, and electrical conductivity of the sintered ceramics were studied systematically. The introduction of (Li_0.5Sm_0.5)²⁺ ions does not change the bismuth layered structure obviously, but it will overmelt and affect its comprehensive properties with the increase of doping content. At last, the piezoelectric coefficient (d₃₃) of ∼9.6 pC/N and the Curie temperature (T_c) is 921.3 °C, which shows good temperature stability and cycle stability, and the mechanical quality factor (Q_m) reaches 2694.3 for x = 0.01 composition. These results show that BTNO-1LS is an excellent candidate for high temperature piezoelectric ceramics.