The anisotropic conductivity of ferroelectric La2Ti2O7 ceramics

• Published in: Journal of the European Ceramic Society 2017-01, Vol.37 (1), p.137-143
• Main Authors: Gao, Zhipeng, Wu, Lingfeng, Lu, Chengjia, Gu, Wei, Zhang, Tao, Liu, Gaomin, Xie, Qinghai, Li, Ming
• Format: Article
• Language: English
• Subjects: Conductivity; Ferroelectrics; Impedance spectroscopy; Piezoelectric; PLS ceramic
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2016.08.020

•The anisotropic electrical conduction behaviour of the textured La2Ti2O7 ceramics was studied using impedance spectroscopy and Seebeck coefficient measurements.•The results reveal that the grain (bulk) conductivity along the perpendicular direction is more than ∼50 times higher than that along the parallel direction below ∼600°C.•The activation energy (Ea) for conduction is 0.67eV along the perpendicular direction, much smaller than the 1.45eV along the parallel direction.•The electrical conduction, along both perpendicular and parallel directions of the textured ceramic, is dominated by p-type hole conduction.•No appreciable contribution of oxide ion conduction to the measured conductivity is observed. Ferroelectric ceramics with perovskite-like layered structure (PLS) have good potential for high temperature piezoelectric applications due to their high Curie point (Tc). The electrical conduction behaviour of these materials is a critical parameter to consider for practical applications. In this study, we prepared textured ceramics of the typical PLS ferroelectric La2Ti2O7 using spark plasma sintering and investigated the electrical properties using impedance spectroscopy and Seebeck measurements. The results reveal that the bulk resistivity along the parallel direction is much higher than that along the perpendicular direction. The activation energy for conduction (Ea) along the parallel direction is 1.45eV, which is close to half of the optical band gap and much higher than the 0.67eV along the perpendicular direction. Electrical conduction along both the directions is dominated by p-type hole conduction. No appreciable contribution of oxide ion conduction to the measured conductivity is observed.