Depolarization temperature and piezoelectric properties of (Bi1/2Na1/2)TiO3–(Bi1/2Li1/2)TiO3–(Bi1/2K1/2)TiO3 lead-free piezoelectric ceramics

Abstract The phase transition temperature and piezoelectric properties of x (Bi 1/2 Na 1/2 )TiO 3 – y (Bi 1/2 Li 1/2 )TiO 3 – z (Bi 1/2 K 1/2 )TiO 3 [ x + y + z = 1] (abbreviated as BNLKT100 y –100 z ) ceramics were investigated. BNLKT100 y –100 z ceramics were prepared by conventional ceramic fabrication. The depolarization temperature T d was determined by the temperature dependence of the dielectric and piezoelectric properties. This study focuses on the effect of Li 1+ and K 1+ ions on T d and the piezoelectric properties of BNT ceramics. BNLKT100 y –100 z ( y = 0–0.08) has a morphotropic phase boundary (MPB) between rhombohedral and tetragonal phases at z = 0.18–0.20, and high piezoelectric properties were obtained at the MPB composition. The piezoelectric constant d 33 increased with increasing y ; however, T d decreased above y = 0.06. The d 33 and T d values of BNLKT4-20 and BNLKT8-20 were 176 pC/N and 171 °C, and 190 pC/N and 115 °C, respectively.