García-Martín Susana, Alario-Franco Miguel A, Ehrenberg Helmut, Rodríguez-Carvajal Juan, Amador Ulises
Departamento de Química Inorgánica, Facultad de Ciencias Químicas, Universidad Complutense, 28040- Madrid, Spain.
J Am Chem Soc. 2004 Mar 24;126(11):3587-96. doi: 10.1021/ja038410l.
Three representative oxides of the La(2/3)(-)(x)()Li(3)(x)()TiO(3) system have been studied by selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM), and powder synchrotron X-ray diffraction. HRTEM showed that the materials have a complex microstructure. The SAED and HRTEM results have allowed us to propose a model to refine the crystal structure of these oxides that also accounts for their microstructure. The materials have a perovskite-related structure with a diagonal unit cell ( radical 2a(p) x radical 2a(p) x 2a(p)) as a consequence of the tilting of the TiO(6) octahedra. Ordering of lanthanum and lithium ions and vacancies along the 2a(p)-axis, as well as displacements of titanium ions from the center of the octahedra, have been determined. The size and shape of the domains have been obtained from the synchrotron X-ray diffraction data; in addition, other extended defects such as strains and compositional fluctuations have been detected.
通过选区电子衍射（SAED）、高分辨率透射电子显微镜（HRTEM）和粉末同步加速器X射线衍射对La(2/3)(-)(x)()Li(3)(x)()TiO(3)体系的三种代表性氧化物进行了研究。HRTEM表明这些材料具有复杂的微观结构。SAED和HRTEM结果使我们能够提出一个模型来细化这些氧化物的晶体结构，该模型也考虑了它们的微观结构。由于TiO(6)八面体的倾斜，这些材料具有与钙钛矿相关的结构，其对角线晶胞为（根号2a(p)×根号2a(p)×2a(p)）。已确定镧离子、锂离子和空位沿2a(p)轴的有序排列，以及钛离子从八面体中心的位移。通过同步加速器X射线衍射数据获得了畴的尺寸和形状；此外，还检测到了其他扩展缺陷，如应变和成分波动。
