Piezoelectric and Ferroelectric Properties of Li-Doped (Bi0.5Na0.5)TiO3-(Bi0.5K0.5)TiO3-BaTiO3 Lead-Free Piezoelectric Ceramics

The piezoelectric and ferroelectric properties of 0.852[Bi-0.5(Na(1-x)Lix)(0.5)]TiO3-0.110(Bi0.5K0.5)TiO3-0.038BaTiO(3) (x=0, 0.02, 0.05, 0.10, 0.15, and 0.30, abbreviated as BNKLBTx) lead-free piezoelectric ceramics were prepared by conventional ceramic processing. X-ray diffraction on the samples revealed that Li+ ions diffused into the Bi0.5Na0.5TiO3 lattices (A-site) and formed a solid solution with a single perovskite structure. All the samples could be sintered at 1160 degrees-1180 degrees C, with the density being on the order of > 95% of the theoretical. The ceramics with x=0.10 exhibited the highest properties, with the piezoelectric coefficient being on the order of d(33)=235 pC/N, while the electromechanical coupling factors were found to be k(p)=0.30 and k(t)=0.45, respectively. The dielectric, pyroelectric, electromechanical, and ferroelectric behaviors were investigated as a function of temperature. It was found that the depolarization temperature T-d showed a strong dependence on the content of Li+ addition, shifting to a lower temperature with increasing Li+ dopant.