Synthesis and ionic conductivity of Li_xLa_(1−x)/3Nb_1−yTa_yO₃ solid solutions

抄録

In this study, solid solutions of double-perovskite-type Li_xLa_(1−x)/3Nb_1−yTa_yO₃ (x = 0.1, y = 0.0–1.0) were synthesized by solid-state reaction. We successfully prepared tetragonal Li_0.1La_0.3Nb_1−yTa_yO₃ single phases by increasing the reaction temperature and the Ta composition. The lattice constants of Li_0.1La_0.3Nb_1−yTa_yO₃ were observed to increase with increasing Ta composition, and densified Li_0.1La_0.3Nb_1−yTa_yO₃ pellets composed of larger grains than Li_0.1La_0.3NbO₃ and Li_0.1La_0.3TaO₃ were obtained. The relationship between the Nb–Ta solid solution in Li_0.1La_0.3Nb_1−yTa_yO₃ and ionic conductivity was investigated, which revealed that Li_0.1La_0.3Nb_1−yTa_yO₃ (y = 0.2) exhibited maximum ionic conductivity (σ = 7.78 × 10⁻⁵ S cm⁻¹) at room temperature and that ionic conductivity decreased with increasing Ta composition. The activation energies of Li_0.1La_0.3Nb_1−yTa_yO₃ were found to be 0.34–0.38 eV and increased with increasing Ta composition.