Phase transition behavior and piezoelectric properties of low-Li and high-Sb modified KNN based piezoceramics

(Na(0.5)K(0.5))(0.975)Li(0.025)Nb(0.82-x)Sb(x)Ta(0.18)O(3) lead-free piezoceramics were prepared by the conventional solid-state sintering method. All samples possess a pure perovskite phase, and no secondary phase could be certified. The crystal structure changes from tetragonal to pseudo-cubic with increasing amount of Sb. The ferroelectric Curie temperature (T(c)) shifts to lower temperature while the tetragonal to orthorhombic phase transition temperature (T(o-t)) shows no obvious change with increasing Sb(5+). Enhanced piezoelectric and electromechanical properties are obtained with x = 0.06: d(33) = 352 pC/N, kp = 47% and k(t) = 38%, showing that they could be promising candidates as lead-free piezoelectric materials. (C) 2011 Elsevier B.V. All rights reserved.