کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9781860 | 1511638 | 2005 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Structural characterization of nanocrystalline CrOOH·2H2O aerogel by X-ray diffraction
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
مواد الکترونیکی، نوری و مغناطیسی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The nanostructured powder prepared by critical CO2 extraction of the urea-assisted wet chromia gel mixture at 373 K in vacuum was studied by X-ray diffraction techniques. Thermoanalytical methods showed the presence of the lattice water molecules in the resulting phase corresponding to a chemical formula CrOOH·2H2O. The CrOOH·2H2O nanocrystals of 3-5 nm in diameter were observed in transmission electron microscopy and their structure was derived from the Rietveld analysis in which the disorder contribution to the X-ray scattering was implemented. The structural model shows that the hexagonal unit cell of α-CrOOH undergoes monoclinic distortion with half of the Oâ2 anions and OHâ groups being replaced by bonded water molecules in the three-dimensional packing resulting in half of the sites in regular Cr+3 octahedra being vacant. Further examination of the quasi-crystalline disordered state of the CrOOH·2(H2O) nanocrystals was performed by model independent method of Radial Distribution Function (RDF). This complementary technique is sensitive to the molecular composition and allows to assess the average atomic (or electron) density distribution and the spacings of the atomic arrangements in the nearest neighbor shells comprising the range of the crystalline order in the structure of this material.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Physics and Chemistry of Solids - Volume 66, Issue 1, January 2005, Pages 81-90
Journal: Journal of Physics and Chemistry of Solids - Volume 66, Issue 1, January 2005, Pages 81-90
نویسندگان
A. Erenburg, E. Gartstein, M. Landau,