Low temperature fabrication of lead-free KNN-LS-BS ceramics via the combustion method

Lead-free piezoelectric 0.992(0.95K0.5Na0.5NbO3–0.05LiSbO3)–0.008BiScO3; KNN-LS-BS ceramics were successfully prepared using the combustion method. The highest % perovskite phase was found in the sample calcined at 700 °C for 1 h. The structural phase of orthorhombic structure was also detected in this sample. For the sintered ceramics, a pure tetragonal perovskite phase was observed in the samples sintered between 1025 and 1100 °C. The microstructure of ceramics showed a square or rectangular shape and the average grain size increased with increasing of sintering temperature. The density of the ceramics increased with increasing of sintered temperature up to 1075 °C, were it reached 97.5% of theoretical density and then dropped in value when the sintered temperature further increased. The excellent electrical properties of εr at Tc=6600, tanδ at Tc=0.04, Pr (at 40 kV/cm)=19.4 μC/cm2 and Ec (at 40 kV/cm)=24.1 kV/cm were obtained in the most dense ceramic. The results indicate that the KNN-LS-BS ceramics are promising lead-free piezoelectric materials.