کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1332738 979052 2008 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Isomorphous substitution of europium for strontium in the structure of synthetic hydroxovanadate
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی معدنی
پیش نمایش صفحه اول مقاله
Isomorphous substitution of europium for strontium in the structure of synthetic hydroxovanadate
چکیده انگلیسی

Polycrystalline strontium–europium hydroxovanadates Sr10−xEux(VO4)6(OH)2−xOx were synthesized and studied by X-ray powder diffraction, infrared absorption and diffuse-reflectance spectroscopies and also thermogravimetry. The single-phase region of isomorphous substitution of Eu for Sr in hydroxovanadate has been found to lie in the compositional interval 0⩽x⩽0.18 at 800 °C. Refinement of X-ray diffraction (XRD) patterns by the Rietveld method shows that Eu substitutes for Sr preferentially at the Sr(1) sites of the apatite structure. The substitution results in a more uniform distribution of Sr–O bond lengths in coordination polyhedra both around Sr (1) and Sr (2) sites and also in a slight contraction of the vanadate anion VO43−. Synthetic Sr hydroxovanadates absorb a considerable amount of water in two forms: capillary condensed and chemically combined. The latter form may be absorbed at temperatures as high as 500 °C.

The results of this paper contribute to a general picture of substitution effects of the rare-earth (RE) elements in the apatite structure. The dependence of the substitution limit xmax in Sr10−xREx(VO4)6(OH)2−xOx on the atomic number of the RE element is shown here with the present data marked with red color.Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Solid State Chemistry - Volume 181, Issue 9, September 2008, Pages 2386–2392
نویسندگان
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