Lead-free (Li, Na, K)(Nb, Sb)O₃ piezoelectric ceramics: effect of Bi(Ni_0.5Ti_0.5)O₃ modification and sintering temperature on microstructure and electrical properties

Lead-free (1 − x)(K_0.475Na_0.475Li_0.05)(Nb_0.95Sb_0.05)O₃–xBi(Ni_0.5Ti_0.5)O₃ [(1 − x)KNNL–xBNiT] piezoelectric ceramics were prepared by conventional solid-state sintering. The effect of BNiT addition and sintering temperature on phase structure, microstructure, and dielectric and piezoelectric properties of (1 − x)KNNL–xBNiT ceramics was investigated. The results reveal that the addition of small amounts of BNiT causes significant changes in microstructures, crystalline structures, and dielectric and piezoelectric properties. The T _c values and dielectric constant at T _c of (1 − x)KNNL–xBNiT ceramics are increased obviously with 0.2 % BNiT addition and decreased with further increasing BNiT content. Enhanced piezoelectric properties are obtained for the sample with x = 0.4 % and synthesized at optimal temperature of 1100 °C, in which d ₃₃ and k _p are 253 pC/N and 0.52, respectively. These results show that (1 − x)KNNL–xBNiT ceramics are promising lead-free piezoelectric materials.