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

Lead-free (K0.17Na0.83−xLix)NbO3 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 (TO-T) and tetragonal-cubic (TC) phase transition temperatures change linearly with increasing Li content and the sample with x = 0.06 exhibits the highest TC of 429 °C and lowest TO-T of 181 °C. Because of the wide apart of TO-T from room temperature, no polymorphic phase structures were obtained and the piezoelectric strain coefficient d33 and piezoelectric coupling constant kp varied between low values of 57, 61 pC/N and 0.18, 0.24, respectively with less than 6 mol% Li doping.