Effect of Li on the microstructure and electrical properties of (K0.17Na0.83)NbO3 lead-free piezoceramics

Abstract Lead-free (K 0.17 Na 0.83−x Li x )NbO 3 piezoceramics were synthesized by conventional solid state sintering and the effect of Li on the microstructure and electrical properties was investigated. The experimental results show that 4 mol% Li doping facilitates the grain growth and increases the density of the ceramics. The measurement of dielectric properties reveals that the orthorhombic-tetragonal ( T O-T ) and tetragonal-cubic ( T C ) phase transition temperatures change linearly with increasing Li content and the sample with x  = 0.06 exhibits the highest T C of 429 °C and lowest T O-T of 181 °C. Because of the wide apart of T O-T from room temperature, no polymorphic phase structures were obtained and the piezoelectric strain coefficient d 33 and piezoelectric coupling constant k p varied between low values of 57, 61 pC/N and 0.18, 0.24, respectively with less than 6 mol% Li doping.