Abstract: Leadfree BiFeO3 (BF) doped K0.5Na0.5NbO3 (KNN) piezoelectric ceramics were prepared by a traditional ceramic processing. The effects of sintering temperature and holding time on the microstructure, phase transition, density and piezoelectric properties of BF doped KNN ceramics were investigated. The results show that all specimens exhibit a pure perovskite structure. The surface micrograph, density and piezoelectric properties of the ceramics depend strongly on the sintering temperature and holding time. When being sintered at temperature from 1100℃ to 1150℃ for 3h, the d33, Kp and Qm of the ceramics increase, while the tanδ decreases with the sintering temperature increasing. When being sintered at 1150℃ for 1h to 3h, the d33, Kp and Qm of the ceramics increase firstly and then remain unchanged, while the tanδ decreases firstly and then also remains unchanged with the holding time increasing. The BFdoped KNN ceramics sintered at 1150℃ for 2h exhibit excellent properties (ρ=4.50g/cm³， d₃₃=132pC/N, K_p=45%, Q_m=333.73, tanδ=2.39%).

Key words: lead-free piezoceramics, K_0.5Na_0.5NbO₃, sintering temperature, piezoelectric properties