Phase transition and electrical properties in the Li-modified BiNaTiO-based lead-free ceramics.

Phase transition and electrical properties were demonstrated for a Li-modified BiNaTiO-based solid solution. (0.935 − x)BiNaTiO− xBiLiTiO− 0.065BaTiO with 0.5 mol% Mn doping was prepared by a conventional solid state reaction method. Close inspection of X-ray diffraction patterns indicated that no characteristic peaks splitting happened, indicating the pseudocubic structure for all the compositions. At a critical composition x of 0.06, optimized performance was obtained with piezoelectric constant d of 176 pC/N, electromechanical coupling factors k of 0.33, and k of 0.52, respectively. In addition, it was found that the Li substitution could lead to a disruption of long-range ferroelectric order and obtain enhanced frequency dispersion behavior accompanied with the decreasing of the depolarization temperature T, which was responsible for the observed weaker ferroelectric polarization and electromechanical response. The composition induced structure evolution was also discussed combined with the Raman spectroscopy. [ABSTRACT FROM AUTHOR]