La2/3−xLi3xTiO3 (x = 0.12) were investigated by using neutron diffraction and transmission electron microscopy. The results were compared with those of previous studies on La2/3−xLi3xTiO3 compounds, and the relationship between their structures and ionic conduction was considered. Rietveld refinement, using neutron diffraction data, revealed that the average structure (Cmmm) of furnace-cooled Li-rich La2/3−xLi3xTiO3 (x = 0.12) involved an alternating ordered arrangement of La along the c-axis, and an antiphase-tilt of TiO6 octahedra along the b-axis; as in Li-poor La2/3−xLi3xTiO3 (x = 0.05). It was found that the strong correlation between structure and percolative diffusion pathways in the perovskites was due mainly to the ordered arrangement of La ions, and to a bottleneck square, surrounded by four O ions, defined by the distortion and tilt of TiO6 octahedra. In addition, the 90°-oriented micro-domain structure, which also influenced percolative pathways in La2/3−xLi3xTiO3, was observed using transmission electron microscopy.

Structural Investigations of Migration Pathways in Lithium Ion-Conducting La2/3−xLi3xTiO3 Perovskites. Y.Inaguma, T.Katsumata, M.Itoh, Y.Morii, T.Tsurui: Solid State Ionics, 2006, 177[35-36], 3037-44