High performance lead-free piezoelectric ceramics in the (K,Na)NbO3-LiTaO3 solid solution system

A new solid solution system, namely {(K0.5Na0.5)(1-x)Li,}(Nb1-yTay)O-3, with full density, a large piezoelectric constant and high stability has been developed. The system has a morphotropic phase boundary (MPB) between orthorhombic and tetragonal. The MPB gives the largest piezoelectric d constant at {(K0.5Na0.5)(0.97)Li-0.03}(Nb0.8Ta0.2)O-3, which exhibits a piezoelectric actuator constant d(33) of 230 pm/V 2.34 times that of Pure (K0.5Na0.5)NbO3 (KNN). Also, it gives a piezoelectric coupling Kp value (0.505), a dielectric constant (1256), and an elastic compliance (10.9 TPa-1) 1.51, 2.93, and 1.14 times those of pure KNN, respectively. The long-term stability of the dielectric loss was demonstrated to be far superior to that of pure KNN.