Rietveld Refinement and HRTEM Simulation of Calcium -Lead Apatites
نویسندگان
چکیده
منابع مشابه
Rietveld refinement of the crystallographic structure of human dental enamel apatites
X-ray powder diffraction and chemical analyses show that mammalian dental enamel apatite is an impure form of hydroxylapatite, Ca10(PO4)6(OH)2 (structure described in Elliott 1994). The major difference of enamel apatite from hydroxylapatite is in the presence of about 3 wt% CO3. Details of the crystallographic structures of carbonate-containing apatites (including minerals) are important becau...
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Extraction of reliable bond distances and angles for Ca10(VxP1-xO4)6F2 apatites using standard Rietveld refinement with Cu Kalpha X-ray powder data was significantly impaired by large imprecision for the O-atom coordinates. An initial attempt to apply crystal-chemical Rietveld refinements to the same compounds was partly successful, and exposed the problematic determination of two oxygen-metal-...
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Y(2)GeO(5) (yttrium germanium penta-oxide) was synthesized by solid-state reaction at 1443 K. The arrangement, which has monoclinic symmetry, is isostructural with Dy(2)GeO(5) and presents two independent sites for the Y atoms. Around these atoms there are distorted six-coordinated YO(6) octa-hedra and seven-coordinated YO(7) penta-gonal bipyramids. The YO(7) polyhedra are linked together, shar...
متن کاملGlobal Rietveld Refinement
Global optimisation methods of structure determination from powder diffraction data have risen to prominence in a relatively short space of time and they now constitute a key approach in the examination of polycrystalline molecular organic materials. A correctly formulated global optimisation approach may be regarded as a "global Rietveld refinement" that is capable of delivering accurate cryst...
متن کاملParametric Rietveld refinement
In this paper the method of parametric Rietveld refinement is described, in which an ensemble of diffraction data collected as a function of time, temperature, pressure or any other variable are fitted to a single evolving structural model. Parametric refinement offers a number of potential benefits over independent or sequential analysis. It can lead to higher precision of refined parameters, ...
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ژورنال
عنوان ژورنال: Microscopy and Microanalysis
سال: 2002
ISSN: 1431-9276,1435-8115
DOI: 10.1017/s1431927602107495