Perovskite lithium and bismuth modified potassium-sodium niobium lead-free ceramics for high temperature applications

摘要

[(K_((1-x)/2)Na_((1-x)/2)Li_x)_(1-3y)Bi_y]NbO_3 (abbreviated as KNLBN) ceramics were prepared by conventional solid-state sintering. The addition of Li~+ and Bi~(3+) makes the orthorhombic-tetragonal phase transition temperature (T_(O-T)) decrease from 200 ℃ for pure (K_(0.5)Na_(0.5))NbO_3 ceramics to -10 ℃ for KNLBN ceramics (x=0.06, y=0.005), while maintaining high Curie temperature (T_C =455 ℃) and piezoelectric properties (d_(33)= 185 pC/N, k_p=043, k_t=0.45, ε_(33) ~T/ε_0=1020, and tan δ=0.023) at room temperature. In addition, good temperature stability of electrical properties is obtained in KNLBN ceramics (x=0.06, y=0.005) owing to the decrease of T_(O-T). These results indicate that KNLBN (x=0.06, y=0.005) ceramic is a promising lead-free piezoelectric candidate material for high temperature applications.