Phase structure and electrical properties of K0.5Na0.5(Nb0.94Sb0.06) O3-LiTaO3 lead-free piezoelectric ceramics

Lead-free piezoelectric ceramics (1-x) K0.5Na0.5( Nb0.94Sb0.06)O-3-xLiTaO(3) have been fabricated by a conventional solid-state sintering technique. The ceramics can be well sintered at 1080 - 1110 degrees C and exhibit a dense, single-phase perovskite structure at x <= 0.06. Coexistence of the tetragonal and orthorhombic phases is formed in the ceramics with 0.02 < x < 0.05, leading to a significant enhancement in piezoelectric properties. For the ceramic with x = 0.04, the piezoelectric properties become optimum: piezoelectric constant d(33) = 271 pCN(-1), electromechanical coupling coefficients k(P) = 0.53 and k(t) = 0.43. Moreover, the ceramics are non-deliquescent and exhibit excellent performance in transducer applications, indicating that the ceramics are ready for replacing lead-containing ceramics in practical applications.