IMF2017

The Li⁺-containing additives is an useful sintering aid to decrease the sintering temperature. Li ions can incorporate into the lattice of BaTiO₃ based ceramics during the sintering process. However, it is not clear where Li+ ions located in A or B site , which caused some confusion in understanding the nature of doping Li cations in the perovskite structure. In this report, the Li-doped (Ba_0.85Ca_0.15)(Ti_0.9Zr_0.1)O₃ (BCZT) and BaTiO₃ ceramics were investigated. It is found that the Li doping increases the activation energy of the ionic conduction and hardening the piezoelectric properties of BCZT ceramics. For Ba_1-xLi_xTiO_3-x/2, BaTi_1-xLi_xO_3-3x/2 and BaTiO_3+x+ (x/2)Li₂CO₃ ceramics (x = 0, 0.01, 0.03, 0.05, 0.07), the results show that Li⁺ prefers to selectively substitute Ba²⁺ at A site then to substitute when the concentration of Li⁺ is below 1%, then enters into B site for Ti⁴⁺ at B site in BaTiO₃+(x/2)Li₂CO₃ ceramics. All Li-doped BaTiO₃-based ceramics exhibit double hysteresis loops. Based on various measurements and the first-principles calculations, it is proposed that the interaction between Li, especially at B-site, and O-vacancy and the dipolar defect Li-OV and their clustering should play an important role in the electrical and piezoelectric properties.