Sintering characteristic and piezoelectric properties of lead-free (K_0.5Na_0.5)NbO₃-LiNbO₃ ceramics

Lead-free (1-x)(1-x) (K_0.5Na_0.5) NbO₃-xLiNbO₃ piezoelectric ceramics were prepared by a traditional ceramic processing. The sintering characteristic, the microstructure and electrical properties of (1-x) (K_0.5Na_0.5) NbO₃-LiNbO₃ ceramics were investigated. Results show that all specimens exhibit a pure perovskite structure and the phase structure at room temperature transforms from orthorhombic to tetragonal with the increase of LiNbO3.The microstructure of (1-x) (K_0.5Na_0.5) NbO₃-LiNbO₃ ceramics exhibits apparent difference due to different amounts of LiNbO₃. The sinterability of (1-x) (K_0.5Na_0.5) NbO₃-LiNbO₃ is improved and the sintering temperature is lower than that of pure KNN ceramics. The (1-x) (K_0.5Na_0.5) NbO₃-LiNbO₃ (x=0.06) ceramics exhibits an excellent piezoelectric properties with the piezoelectric constant d₃₃, the electromechanical coupling coefficients k_p and k_t of 205pC/N, 40.3% and 49.8%, respectively.