Study on the structural change and lithium ion conductivity for the perovskite-type LaAlO3–La0.50Li0.50TiO3 solid solution

The structure and the lithium ion conductivity in the perovskite-type xLaAlO3–(1 − x)La0.50Li0.50TiO3 solid solution (0.0 ≤ x ≤ 1.0) were investigated. LaAlO3 oxide could be incorporated into La0.50Li0.50TiO3 at any composition of x, indicating that the Al3+ ions can be completely substituted for the Ti4+ ions. By increasing the LaAlO3 content, the La0.50Li0.50TiO3 structure changed from tetragonal via cubic to rhombohedral, in which their perovskite primitive cells have cubic symmetry. The highest Li+ ionic conductivity of 8.98 × 10−4 S cm−1 at 298 K, and the lowest activation energy of 0.25 eV appear at x = 0.1 and 0.2, respectively. The ionic conductivity drastically decreases in the vicinity of x = 0.4. When increasing the LaAlO3 content over 0.4, the ionic conduction properties vanish. The result indicates that the samples with x = 0–0.4 have the Li+ ion conduction properties to be used as solid electrolytes of electrochemical devices.