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Lead-free (1-x)(Na0.5K0.5)NbO3-xLiNbO3, i.e., NKN-LNx (x =0.0, 0.1, 0.2, 0.3, 0.4 mol) was prepared using the conventional solid state reaction method. The effects of LN mixing on the ferroelectric properties of NKN-LNx ceramics were studied using a dielectric constant and P-E (Polarization-electric field) measurements. Ferroelectricity was observed in the composition for x approximately varying between 0.0 and 0.4. Minimum remanent polarization 2Pr=5 C/cm2 was achieved in the composition for x = 0.2. The ferroelectric phase transition temperature TC increased with increasing LN content. The ferroelectric phase transition of NKN-LNx (x ≥ 0.1) is a second-order phase transition,and that of NKN-LNx (x ≤ 0.2) is a first-order phase transition. These results indicate that the ferroelectric phase transition temperature of NKN-LNx change from that of second-order to weak first-order phase transition according to the LN content.