Effects of K∕Na ratio on the phase structure and electrical properties of (KxNa0.96−xLi0.04)(Nb0.91Ta0.05Sb0.04)O3 lead-free ceramics

( K x Na 0.96 − x Li 0.04 ) ( Nb 0.91 Ta 0.05 Sb 0.04 ) O 3 (x=0.32–0.56) lead-free piezoelectric ceramics were prepared by conventional sintering. The effects of K∕Na ratio on the phase structure and electrical properties of the ceramics were studied. These results indicate that the phase structure undergoes a transition from orthorhombic to tetragonal phase with increase of x. The ceramics with x=0.38 exhibit enhanced electrical properties (d33∼306pC∕N; kp∼48%; kt∼49%; Tc∼337°C; ϵr∼1327; tanδ∼2.5%; Pr∼34.9μC∕cm2; Ec∼11.3kV∕cm). Enhanced electrical properties of the ceramics should be attributed to the polymorphic phase transition near room temperature. These results show that the ceramic with x=0.38 is a promising lead-free piezoelectric material.