Effects of W2/3Bi1/3 substitute on piezoelectric properties of KNN-based ceramics

Abstract Lead-free (K 0.5 Na 0.5 ) 0.94 Li 0.06 (W 2/3 Bi 1/3 ) x Nb 1 −  x O 3 ceramics were prepared by conventional solid-state sintering. The samples were characterized by X-ray techniques and scanning electron microscopy. The piezoelectric and dielectric properties were also investigated by varying the doping amount of W 2/3 Bi 1/3 . All the samples have tetragonal perovskite structure, and no secondary phases are formed in the range detected. Proper amount of W 2/3 Bi 1/3 improves the piezoelectric activity, playing a soft doping role. The piezoelectric constant d 33 and planar mode electromechanical coupling coefficient k p show maximum values of 282 pC/N and 45% in the ceramics with x  = 0.008. The results show that the introduction of constructed quinquevalent (W 2/3 Bi 1/3 ) 5 + cation is very effective in improving the electrical properties of KNN-based ceramics.