Structural study of Li2MnO3 by electron microscopy
Structural study of Li2MnO3 by electron microscopy
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DOI：
10.1007/s10853-009-3784-1
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发表时间：
2009-08
影响因子：
4.5
通讯作者：
C. Lei;J. Wen;M. Sardela;J. Bareño;I. Petrov;S. Kang;D. Abraham
中科院分区：
文献类型：
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作者：
C. Lei;J. Wen;M. Sardela;J. Bareño;I. Petrov;S. Kang;D. Abraham
通过结合使用 X 射线衍射 (XRD)、选区电子衍射 (SAED)、高分辨率电子显微镜 (HREM) 和扫描透射电子显微镜中的 0.1 nm 探针高角度环形暗场成像 (HAADF)，获得了高质量 Li2MnO3 材料的详细晶体学数据。将高纯度 Li2MnO3 粉末在 950 °C 下退火 3 天，以获得平均尺寸为 3.0 ± 1.5 μm 的基本无缺陷的晶粒。 Rietveld 精修表明 C2/m 空间群提供了 XRD 数据的最佳拟合。在无缺陷氧化物颗粒上沿不同区域轴获得的电子衍射图案可以唯一地索引到单斜结构。无缺陷晶粒的 HREM 和 HAADF 图像与 Li-Mn-Mn- 排列一致，即过渡金属平面中的锂排序。低倍率 TEM 图像偶尔会显示氧化物颗粒内的堆叠缺陷。含有缺陷的样品区域的 HREM 图像显示，单斜晶系内的堆垛层错密度较低，从而形成三角 P3112 局部排列。
Detailed crystallographic data on high-quality Li2MnO3material has been obtained using a combination of X-ray diffraction (XRD), selected-area electron diffraction (SAED), high-resolution electron microscopy (HREM), and 0.1 nm probe high-angle annular dark-field imaging (HAADF) in a scanning transmission electron microscope. A high-purity Li2MnO3powder was annealed at 950 °C for 3 days to obtain predominantly defect-free grains which average size was 3.0 ± 1.5 μm. Rietveld refinement indicated that theC2/mspacegroup provided the best fit for the XRD data. Electron diffraction patterns obtained along various zone axes, on defect-free oxide particles, could be uniquely indexed to the monoclinic structure. HREM and HAADF images of defect-free grains were consistent with a Li–Mn–Mn– arrangement, i.e., lithium ordering in the transition metal planes. Low-magnification TEM images occasionally revealed stacking defects within oxide particles. HREM images of sample areas containing defects revealed a low density of stacking faults within the monoclinic sequence, resulting in a trigonalP3112local arrangement.