Lead-free NKN-LST ceramics with a content of CuO were fabricated by a conventional mixed oxide method. The results indicate that the content of CuO significantly influences the sintering, microstructure, phase transition and electrical properties of NKN-LST ceramics. For the NKN-LST-xCuO ceramics sintered at 1050oC, the bulk density increased with the content of CuO and showed a maximum value at a content of 2.0 mol% CuO. The Curie temperature of the NKN-LST-xCuO ceramics slightly decreased towards a lower temperature with increasing CuO content. The dielectric constant, piezoelectric constant and electromechanical coupling factor increased with a small amount of CuO content, which might be due to the increase in density. A high d33 = 153 pC/N, kp = 35% and ε = 925 were obtained for the NKN-LST-0.5CuO ceramics sintered at 1050 oC for 2 h.

Keywords: Lead-free, NKN-LST, CuO, Piezoelectric constant, Dielectric const