Influence on structure and properties of CuO addition to KNN–LS–BF piezoelectric ceramics

(1 − x)[0.98(0.95Na0.5K0.5NbO3–0.05LiSbO3)–0.02BiFeO3]–xmol%CuO (KNN–LS–BF–xCuO) lead-free piezoelectric ceramics have been synthesized by the conventional solid-state reaction process. It is found that the addition of CuO has not changed the phase structure of KNN–LS–BF ceramics, but has significant influence on their crystalline structure and properties. The SEM images reveal that the amount of holes are reduced and the grain become more tightly arranged as the CuO content x increasing. With the increase of CuO content x, the d33, kp, tanδ, Qm exhibit different variation trend and have been improved obviously when x < 0.15, but excessive CuO would degrade the comprehensive properties of KNN–LS–BF–xCuO ceramics. The best specimens of KNN–LS–BF–xCuO ceramics were fabricated when x = 0.15 at 1060 °C, relating constants respectively are: d33 = 243pC/N, kp = 0.40, er = 1506, tanδ = 2.85 %, Qm = 21.87.