Crystal structure of La<sub>0.4sub>Sr<sub>0.6sub>CoO<sub>2.71sub> investigated by TEM and XRD

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• 作者：C. Gspan ; W. Grogger ; B. Bitschnau ; E. Bucher ; W. Sitte ; F. Hofer
• 关键词：Perovskite superstructure ; TEM ; Electron diffraction ; XRD
• 刊名：Journal of Solid State Chemistry
• 出版年：2008
• 出版时间：November 2008
• 年：2008
• 卷：181
• 期：11
• 页码：2976-2982
• 全文大小：1453 K

文摘

The structure of the oxygen-deficient perovskite La<sub>0.4sub>Sr<sub>0.6sub>CoO<sub>3−sub><sub>δsub> (δ=0.29) was investigated by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). Domains between 50 and 250 nm in size were observed in the electron microscope. Weak superstructure reflections were found with both X-ray and electron diffraction. Investigations of these superstructure reflections by selected area electron diffraction (SAED) and convergent beam electron diffraction (CBED) showed that the domains in a crystal are orientated in a 90° relationship. High-resolution transmission electron microscopy (HRTEM) images from the domain boundary also revealed a 90° orientation dependency. Using the symmetry of CBED patterns, the point group 4/mmm was determined. By comparing reflections from the SAED pattern with possible reflections, the space group I4/mmm (No. 139) could be isolated and finally the crystal structure was refined by Rietveld refinement.