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

Abstract

[ ( K ( 1 − x ) ∕ 2 Na ( 1 − x ) ∕ 2 Li x ) 1 − 3 y Bi y ] Nb O 3 (abbreviated as KNLBN) ceramics were prepared by conventional solid-state sintering. The addition of Li+ and Bi3+ makes the orthorhombic-tetragonal phase transition temperature (TO-T) decrease from 200°C for pure (K0.5Na0.5)NbO3 ceramics to −10°C for KNLBN ceramics (x=0.06, y=0.005), while maintaining high Curie temperature (TC=455°C) and piezoelectric properties (d33=185pC∕N, kp=0.43, kt=0.45, ε33T∕ε0=1020, and tanδ=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 TO-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.