García-Martín Susana, Morata-Orrantía Ainhoa, Alario-Franco Miguel A, Rodríguez-Carvajal Juan, Amador Ulises
Departamento de Química Inorgánica, Facultad de Ciencias Químicas Universidad Complutense, 28040 Madrid, Spain.
Chemistry. 2007;13(19):5607-16. doi: 10.1002/chem.200700235.
The crystal structures of several oxides of the La(2/3)Li(x)Ti(1-x)Al(x)O(3) system have been studied by selected-area electron diffraction, high-resolution transmission electron microscopy, and powder neutron diffraction, and their lithium conductivity has been by complex impedance spectroscopy. The compounds have a perovskite-related structure with a unit cell radical2 a(p)x2 a(p)x radical2 a(p) (a(p)=perovskite lattice parameter) due to the tilting of the (Ti/Al)O(6) octahedra and the ordering of lanthanum and lithium ions and vacancies along the 2 a(p) axis. The Li(+) ions present a distorted square-planar coordination and are located in interstitial positions of the structure, which could explain the very high ionic conductivity of this type of material. The lithium conductivity depends on the oxide composition and its crystal microstructure, which varies with the thermal treatment of the sample. The microstructure of these titanates is complex due to formation of domains of ordering and other defects such as strains and compositional fluctuations.
通过选区电子衍射、高分辨率透射电子显微镜和粉末中子衍射研究了La(2/3)Li(x)Ti(1 - x)Al(x)O(3)体系中几种氧化物的晶体结构，并通过复阻抗谱研究了它们的锂电导率。由于(Ti/Al)O(6)八面体的倾斜以及镧、锂离子和空位沿2a(p)轴的有序排列，这些化合物具有与钙钛矿相关的结构，其晶胞为radical2 a(p)x2 a(p)x radical2 a(p)（a(p) = 钙钛矿晶格参数）。Li(+)离子呈现扭曲的平面四方配位，位于结构的间隙位置，这可以解释这类材料非常高的离子电导率。锂电导率取决于氧化物组成及其晶体微观结构，而微观结构会随样品的热处理而变化。由于有序畴以及应变和成分波动等其他缺陷的形成，这些钛酸盐的微观结构很复杂。
