Structural and electrical properties of AgTaO3-modified (Na 0.465K0.465Li0.07) NbO3 lead-free ceramics

The (1-x)(Na0.465K0.465Li0.07)NbO 3 - xAgTaO3 lead-free ceramics were fabricated by the solid-state reaction process. The densification enhanced with increasing AgTaO3 content, giving maximum relative density of 98% (x = 0.02). Both orthorhombic-tetragonal (TO-T) and tetragonal-cubic (T C) phase transition temperature decreased gradually with the increasing AgTaO3 content. The ceramic with a composition of x = 0.02 exhibited excellent electrical properties: the dielectric constant (εr) = 470, dissipation factor (tan δ) = 0.022, piezoelectric constant d33 = 160 pC/N, and Curie temperature T C = 432°C. These results clearly showed that the 0.98(Na 0.465K0.465Li0.07)NbO3 - 0.02AgTaO3 ceramics are very promising lead-free piezoelectric candidates

Structural and electrical properties of Na0.47K 0.47Li0.06NbO3 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 0.92Na0.47K0.47Li0.06NbO 3-0.08AgSbO3 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)Na 0.47K0.47Li0.06NbO3-xAgSbO 3 ceramics are promising materials for lead-free piezoelectric application