Phase transition behaviour and electrical properties of lead-free (K0.5Na0.5)NbO3–LiNbO3–LiSbO3 piezoelectric ceramics

The ternary system of 0.945(K0.5Na0.5NbO3)–(0.055 − x)LiNbO3–xLiSbO3 [0.945KNN–(0.055 − x)LN–xLS]; x = 0.0–0.055 lead-free piezoelectric ceramics was fabricated by the conventional mixed oxide method with normal sintering. The crystal structure was studied by means of X-ray diffraction (XRD). The results of XRD patterns show that complete solid solutions of the mixed phase between the orthorhombic and tetragonal perovskite phase were observed. The DSC and dielectric data show that the amount of LiSbO3 in K0.5Na0.5NbO3–LiNbO3 solid solution slightly decreases the paraelectric cubic-ferroelectric tetragonal phase transition (TC) to a low temperature. Furthermore, good dielectric and piezoelectric properties were observed at composition, x = 0.03. The polymorphic phase transition between the orthorhombic and tetragonal phases plays a very important role in enhancement of the piezoelectric properties of KNN–LN–LS ceramics.