Growth and characterization of Li3xLa2/3−xTiO3 single crystals with various Li compositions

Li3xLa2/3−xTiO3 (LLT) single crystals with different Li compositions (x = 0.042–0.120) were grown by the traveling solvent floating zone (TSFZ) method. Because this material exhibits incongruent melting behavior, solvent of La2Ti2O7-poor composition rather than Li-rich LLT composition for a LLT feed was used. Crack- and inclusion-free single crystals were obtained for all the compositions. The Li composition in the grown crystals was lower than the nominal composition due to vaporization in the melt during growth. In addition, the anisotropic ionic conductivity of the annealed crystal was maximum at a Li composition of x = 0.059. The ionic conductivity along [100], σ[100] = 1.75 × 10–3 S·cm−1, is higher than that of [001], σ[001] = 7 × 10–4 S·cm−1, and the anisotropy σ[100]/σ[001] was determined to be 2.5.