کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1601668 | 1005208 | 2009 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Local atomic order in the vicinity of Cu2 dumbbells in TbCu7-type YCu6.576 studied by Bragg and total scattering techniques
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
فلزات و آلیاژها
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The crystal structure of YCu6.576, a hyperstoichiometric substitution variant of the CaCu5-structure type, was shown to contain Cu2 dumbbells replacing Y-atoms in a fraction s = 0.19 in the formula Y1âsCu5+2s. The structure type TbCu7 is assigned to the disordered structure (P6/mmm, a = 4.96 Ã
, c = 4.15 Ã
). The local order in the vicinity of the Cu2-dumbbells has been derived from total scattering X-ray synchrotron data via refinement of the atomic pair distribution function (PDF). The coordinating Cu6-hexagon around the dumbbell site shows a shrinkage of 0.33(1)Â Ã
w.r.t. the equivalent environment of the Y-atom. No adjacent Y-atoms are substituted but a hexagonal arrangement of Cu2-dumbbells, separated at least by the vectors â3a and â3b exists in layers perpendicular to c. The stacking along [001] is random and can be modeled locally from the PDF data consistent with both ab- and abc-type stacking. Therefore, the local order is comparable to that in Ni17Th2- and Th2Zn17-structure types. X-ray single crystal analysis and Rietveld refinements of neutron- and X-ray powder data (Bragg diffraction data) of YCu6.576 are consistent with the findings from local crystallography (total scattering data) answering a long-standing question in disordered CaCu5-type based intermetallic structure variants.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Intermetallics - Volume 17, Issue 10, October 2009, Pages 818-825
Journal: Intermetallics - Volume 17, Issue 10, October 2009, Pages 818-825
نویسندگان
Radovan Äerný, Yaroslav Filinchuk, Stefan Brühne,