Phase structure and electrical properties of K_0.5Na_0.5(Nb_0.94Sb_0.06)O₃-LiTaO₃lead-free piezoelectric ceramics

Lead-free piezoelectric ceramics (1-x)K0.5Na0.5(Nb0.94Sb0.06)O3-xLiTaO3have been fabricated by a conventional solid-state sintering technique. The ceramics can be well sintered at 1080-1110 °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 d33= 271 pC N-1, electromechanical coupling coefficients kP= 0.53 and kt= 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.