Perovskite-type solid-state electrolytes, Li_3xLa_2/3–xTiO₃ (LLTO), are considered among the most promising candidates for the development of all-solid-state batteries based on lithium metal. Their high bulk ionic conductivity can be modulated by substituting part of the atoms hosted in the A- or B-site of the LLTO structure. In this work, we investigate the crystal structure and the long-range charge migration processes characterizing a family of perovskites with the general formula La_1/2+1/2xLi_1/2–1/2xTi_1–xAl_xO₃ (0 ≤ x ≤ 0.6), in which the charge balance and the nominal A-site vacancies (n_A = 0) are preserved. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) investigations reveal the presence of a very complex nanostructure constituted by a mixture of two different ordered nanoregions of tetragonal P4/mmm and rhombohedral R3̅c symmetries. Broadband electrical spectroscopy studies confirm the presence of different crystalline domains and demonstrate that the structural fluctuations of the BO₆ octahedra require to be intra- and intercell coupled, to enable the long-range diffusion of the lithium cation, in a similar way to the segmental mode that takes place in polymer-ion conductors. These hypotheses are corroborated by density functional theory (DFT) calculations and molecular dynamic simulations.

中文翻译：

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弛豫对 La1/2+1/2xLi1/2–1/2xTi1–xAlxO3 快离子导体电导率的影响

钙钛矿型固态电解质 Li _{3 x} La _{2/3– x} TiO ₃ (LLTO) 被认为是开发基于锂金属的全固态电池的最有希望的候选者。它们的高体积离子电导率可以通过取代位于 LLTO 结构的 A 位或 B 位的部分原子来调节。在这项工作中，我们研究了具有通式 La _{1/2+1/2 x} Li _{1/2–1/2 x} Ti _{1– x} Al _x的钙钛矿家族的晶体结构和长程电荷迁移过程。 O ₃ (0 ≤ x≤ 0.6)，其中电荷平衡和标称 A 位空位 ( n _A = 0) 被保留。X 射线衍射 (XRD) 和高分辨率透射电子显微镜 (HRTEM) 研究揭示了由四方P 4/ mmm和菱面体R 3̅ c对称性的两种不同有序纳米区域的混合物构成的非常复杂的纳米结构的存在。宽带电光谱研究证实了不同结晶域的存在，并证明了 BO _{6的结构波动}八面体需要在电池内和电池间耦合，以实现锂阳离子的长距离扩散，其方式类似于聚合物离子导体中发生的分段模式。这些假设得到了密度泛函理论 (DFT) 计算和分子动力学模拟的证实。