Piezoelectric and dielectric properties of Bi0.5Na0.5TiO3–Bi0.5Li0.5TiO3 lead-free ceramics

Abstract

(1 − x)Bi0.5Na0.5TiO3–xBi0.5Li0.5TiO3 lead-free ceramics have been prepared by a conventional solid-state reaction method, and their piezoelectric and dielectric properties have been studied. X-ray diffraction studies reveal that Li+ diffuses into the Bi0.5Na0.5TiO3 lattices to form a solid solution with a pure perovskite structure. The addition of Bi0.5Li0.5TiO3 effectively lowers the sintering temperature of the ceramics and greatly assists in the densification of the ceramics. The ceramic with x = 0.075 possesses the optimum piezoelectric properties: piezoelectric coefficient d33 = 121 pC/N and planar electromechanical coupling factor kP = 18.3%. After the partial substitution of Li+ for Na+ in the A-sites of Bi0.5Na0.5TiO3, the ceramics exhibit more relaxor characteristic, which is probably resulted from the cation disordering in the 12-fold coordination sites. The depolarization temperature Td shifts to low temperature with the substitution level x of Li+ for Na+ increasing.