Good temperature stability and high piezoelectric properties of pure and La-doped tetragonal (K0.45Na0.55)0.94Li0.06·TaxNb1−xO3 ceramics

Pure and La-doped tetragonal (K0.45Na0.55)0.94Li0.06·TaxNb1−xO3 lead-free ceramics were prepared by the conventional sintering method. The piezoelectric properties and the temperature dependence of these ceramics were investigated. Both good temperature stability and high piezoelectric properties were obtained in tetragonal-phase (K0.45Na0.55)0.94Li0.06·TaxNb1−xO3 ceramics. La was employed to reduce the effect of PPT and further improve the temperature stability of (K0.45Na0.55)0.94Li0.06·Ta0.35Nb0.65O3 ceramics. 0.5 mol% La-doped (K0.45Na0.55)0.94Li0.06·Ta0.35Nb0.65O3 ceramics show the optimum properties (high piezoelectric properties: d33 = 152 pC/N and kp = 30.5% and good temperature dependence: Δfr/fr   20 °Cmax=0.79% and Δkp/kp   20 °Cmax=2.11% in the temperature region 20–80 °C).