Microstructures and electrical properties of KNbO3 doped (Li,Ta,Sb) modified (K,Na)NbO3 lead-free ceramics by two-step sintering

In this study, 0.95(Na0.52K0.44Li0.04)(Nb0.88Sb0.08Ta0.04)O3–0.05KNbO3 (NKLNST–0.05KN) ceramics were prepared by two-step sintering method. The effects of KN and sintering temperature on the microstructures and piezoelectric properties of NKLNST–0.05KN were discussed. The addition of KN aids plays an important role in grain growth behavior and allows lower first-step sintering temperature. And with the extension of the second-step sintering time, the liquid phase with low Na content forms solid solution with the NKLNST ceramics and the nano-sized white spots with high Na content crystallize on the surface of grains. The P–E hysteresis loops of the ceramics are well-saturated, and NKLNST–0.05KN ceramics demonstrate good piezoelectric property d33=328 pC/N under 1130/950 °C sintered by two-step sintering.

► KNN-based ceramics were prepared by two-step sintering using KN as sintering aids.
► KN aids plays an important role on grain growth behavior and microstructures.
► d33=328 pC/N under 1130/950 °C sintered by two-step sintering.