Structural and electrical properties of Na0.47K0.47Li0.06NbO3 lead-free piezoelectric ceramics modified by AgSbO3

(1−x)Na0.47K0.47Li0.06NbO3 (NKLN)–xAgSbO3 lead-free piezoelectric ceramics were prepared using a reaction sintering method. The effects of AgSbO3 doping on the structural and electrical properties of NKLN ceramics sintered at 1000–1040 °C were studied. The dopant affected densification, phase content, sintering temperature, microstructure and electrical properties. Variations in the relative intensity of X-ray diffraction peaks were consistent with Ag+ and Sb5+ ions substituting on the perovskite lattice to produce a change in the proportions of co-existing tetragonal and orthorhombic phases. Grain growth during secondary re-crystallization was also affected. The temperature of the orthorhombic–tetragonal (O–T) phase transition and the Curie temperature (TC) decreased as a result of AgSbO3 modifications. The dielectric and piezoelectric properties are enhanced for the composition near the orthorhombic–tetragonal polymorphotropic phase boundary. The 0.92Na0.47K0.47Li0.06NbO3–0.08AgSbO3 ceramics exhibited optimum electrical properties (d33=252 pC/N, εr=1450, tan δ=0.02, and TC=280 °C). These results reveal that (1−x)Na0.47K0.47Li0.06NbO3–xAgSbO3 ceramics are promising materials for lead-free piezoelectric application.