In this study, non-stoichiometric 1-x[(K0.5Na0.5)0.97(Nb0.96Sb0.04)O3] + x CeMnO3 + 0.8 mol%CuO + 0.2 wt% Ag2O (x=0, 0.005) ceramics were prepared by a conventional mixed oxide and carbonate method, their dielectric and piezoelectric properties were investigated with the variations of sintering temperature. As CeMnO3 substitution incereased, the density, piezoelectric constant(d33) and dielectric constant(εr) were increased and the mechanical quality factor(Qm) was decreased. At the sintering temperature of 1100℃, the density, electromechanical coupling factor(kp), dielectric constant(εr) and piezoelectric constant(d33) of 0.5mol% CeMnO3 specimen showed the optimun values of 4.475 g/㎤, 0.437, 552 and 166 pC/N, respectively. However, the mechanical quality factor(Qm) showed the minimum value of 380.
