Effects of the addition of Li0.8Ni0.2Nb0.96O3 on the structure and electrical properties of K0.48Na0.52NbO3 lead-free piezoceramics

• A new solid solution system of K0.48Na0.52NbO3–Li0.8Ni0.2Nb0.96O3 was investigated.
• Li0.8Ni0.2Nb0.96O3 was found to act as a sintering aid.
• The Ni2+ ions were confirmed to enter the B-sites and lead to the formation of the secondary phase.
• Qm was improved significantly by increasing Li0.8Ni0.2Nb0.96O3 content.

Lead-free K0.48Na0.52NbO3 (KNN) ceramics doped with Li0.8Ni0.2Nb0.96O3 (LNN) were prepared by the mixed oxide method. The structure, microstructure, and electrical properties of the ceramics were investigated systematically. All the samples exhibited the main orthorhombic perovskite phase structure, and the secondary phase K5.75Nb10.85O30 was detected when x ≥ 0.010. Our work revealed that the Ni2+ ions entered into the B-site and lead to the formation of small amounts of the secondary phase. Moreover, the addition of LNN increased the density of the KNN ceramics. With increasing addition of LNN, the TC increased while the TO-T decreased, respectively. The ceramic doped with 2 mol% LNN exhibited optimum electrical properties with Pr of 23.92 μC/cm2, d33 of 110 ± 3 pC/N, kp of 27.15% and kt of 27.75%. The Qm increased significantly with increasing LNN content, and the maximum value of 195 is obtained at x = 0.035.