Microstructure and electrical properties of Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3-LiNbO3 lead-free piezoelectric ceramics

Lead-free piezoelectric ceramics of (1-x-y)Bi0.5Na0.5TiO3-xBi(0.5)K(0.5)TiO(3)-yLiNbO(3) (BNT-BKT-LN-x/y) have been fabricated by a conventional solid-state reaction method, and their microstructure and electrical properties have been investigated. The results of X-ray diffraction (XRD) measurement show that K+, Li+ and Nb5+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a solid solution with a pure perovskite structure. The BKT and LN addition has no remarkable effect on the crystal structure. However, a significant change in grain size took place. Simultaneously, with increasing amount of LN, the temperature for a ferroelectric-antiferroelectric phase transition is clearly reduced. The temperature dependence of dielectric properties suggests that the ceramics have diffuse-type phase transition characteristics. The piezoelectric constant d(33) and the electromechanical coupling factor k(p) of the ceramics attain maximum values of 195 pC/N and 0.336 at x = 0.18 and y = 0.01. (C) 2008 Elsevier Ltd. All rights reserved.