Direct observations of La ordering and domain structures in La_0.61Li_0.17TiO₃ by high resolution electron microscopy

Abstract

La_0.61Li_0.17TiO₃ microstructures have been studied by high resolution electron microscopy. A local lattice distortion occurs in the vicinity of the domain boundary region due to the twin with an angle of 89°. The average domain size of La_0.61Li_0.17TiO₃ is greater than 20 nm. The domain size and structures of La_0.61Li_0.17TiO₃ differ greatly from those of La-poor compounds, such as La_0.55Li_0.35TiO₃. At a nanoscopic level, microdomains of 20–100 nm in size construct a two-dimensional structure in La-rich compounds, while microdomains of 5–10 nm in size construct a three-dimensional structure in La-poor compounds. In addition, the Li-ion conduction mechanisms for La-rich and La-poor compounds are two- and three-dimensional, respectively.

Keywords:

• ionic conductor
• lanthanum lithium titanate
• transmission electron microscopy
• structural analysis

Acknowledgements

The authors thank Emeritus Professor K. Hiraga of Tohoku University for his useful advice. This work was supported by the Center for Integrated Nanotechnology Support at Tohoku University and the Grant-in-Aid for Scientific Research on Priority Area, ‘Nanoionics (439)’ of Ministry of Education, Culture, Sports, Science and Technology, Japan.