Structure and properties of (1−x)[(K0.5Na0.5)NbO3–LiSbO3]– xBiFe0.8Co0.2O3 lead-free piezoelectric ceramics

Lead-free piezoelectric ceramics (1 − x)[0.95(K0.5Na0.5)NbO3–0.05LiSbO3]–xBiFe0.8Co0.2O3(KNN–LS–xBFC) were prepared by a conventional sintering technique. The effect of BFC content on the structure, piezoelectric and electrical properties of KNN–LS ceramics was investigated. The results reveal that the BFC is effective in promoting the sinterability and the electrical properties of the ceramics sintering at low temperature of 1030°C. The ceramics show a single perovskite structure, in which the tetragonal phase decreases while the orthorhombic phase increases with the increase of x. The more the BFC content is, the smaller and homogeneous grains were formed. With the increase of x, the d33 and the kp increase to a maximum value and then slightly decrease, but the Qm increases continuously. As BFC content increases, the Curie temperature Tc and remnant polarization Pr decrease, but the diffusivity of phase transition in KNN–LS ceramics will intensify and the coercive field Ec fluctuate between 1.16 and 1.51 kV mm −1. The samples with x = 0.004 exhibit optimum electrical properties at room temperature (d33 =268 pC N−1, kp = 52%, er = 1366, tan δ = 2.11%, Tc = 325°C, Pr = 20.4 μC cm−2, Ec = 1.16 kV mm−1).