Phase structure and electrical properties of K_0.5Na_0.5(Nb_0.94Sb_0.06)O₃-LiTaO₃ lead-free piezoelectric ceramics

Lead-free piezoelectric ceramics (1-x)K_0.5Na_0.5(Nb_0.94Sb_0.06)O₃–xLiTaO₃ have 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 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.