Microstructural development of the La0.5Li0.5TiO3 lithium ion conductor processed by the laser floating zone (LFZ) method

La2/3-xLi3xTiO3 (x between 0-0.17) compounds have reached great prominence in recent years due to their high lithium ion conductivity. They present a perovskite-related structure (ABO3) with A-cation deficiency. However, neither the phase diagram nor the solidification processes are well known, which makes the growth of single crystals difficult. La0.5Li0.5TiO3 polycrystalline powder was prepared by the LFZ method and studied by SEM, EDS, XRD and micro-Raman techniques. Three phases were detected: the major phase (A) is a La-Li-Ti-O perovskite with 3x < 0.5, that forms large single crystal grains. Phase B is rutile TiO2 and appears as small precipitates surrounding phase A. Finally, eutectic mixtures of phase A and a third phase (C) containing Ti and O in a ratio lower than 1:2 was seen. Phase C was identified as a Li-Ti oxide, probably Li2Ti3O7. 14 refs.