نتایج جستجو برای: rietveld refinement

تعداد نتایج: 34023  

Journal: :Biophysical journal 2003
Carlo Meneghini Maria Chiara Dalconi Stefania Nuzzo Settimio Mobilio Rudy H Wenk

Bioapatite, the main constituent of mineralized tissue in mammalian bones, is a calcium-phosphate-based mineral that is similar in structure and composition to hydroxyapatite. In this work, the crystallographic structure of bioapatite in human fetuses was investigated by synchrotron radiation x-ray diffraction (XRD) and microdiffraction ( micro -XRD) techniques. Rietveld refinement analyses of ...

2008
Z. Somogyvári E. Sváb Gy. Mészáros K. Krezhov P. Konstantinov T. Ungár J. Gubicza

Neutron diffraction study of nanostructured magnetite was performed at room temperature. The actual grain-size was determined from evaluation of X-ray diffraction profiles by the modified Williamson-Hall plot. The atomic structure parameters and the sublattice magnetic moments were determined using the Rietveld refinement of the neutron diffraction spectra. The sublattice magnetization at the o...

2007
P. S. Whitfield P. W. Stephens

A complex refinement of the structure of the battery cathode material, Li1.2Mn0.4Ni0.3Co0.1O2, using neutron and resonant diffraction data is used to demonstrate SVDdiagnostic as a useful tool to diagnose problems in the least squares normal matrix. SVDdiagnostic examines both the unprocessed and pre-conditioned matrices and outputs a 'condition' number as well as combinations of variables caus...

2009
Ivan V. Ogorodnyk Igor V. Zatovsky Nikolay S. Slobodyanik

Potassium yttrium hafnium tris-(orthophosphate) belongs to the langbeinite-family and is built up from [MO(6)] octa-hedra [in which the positions of the two independent M sites are mutually occupied by Y and Hf in a 0.605 (10):0.395 (10) ratio] and [PO(4)] tetra-hedra connected via vertices into a three-dimensional framework. This framework is penetrated by large closed cavities in which the tw...

2009
Matteo Zoppi Giovanni Pratesi

A structural refinement of a natural sample of a Co-bearing mansfieldite, AlAsO(4)·2H(2)O [aluminium orthoarsenate(V) dihydrate], has been performed based on synchrotron powder diffraction data, with 5% of the octa-hedral Al sites replaced by Co. Mansfieldite is the aluminium analogue and an isotype of the mineral scorodite (FeAsO(4)·2H(2)O), with which it forms a solid solution. The framework ...

2011
Bai-Chuan Zhu Kai-Bin Tang

Potassium lanthanum titanate(IV), KLaTiO(4), has been synthesized by conventional solid-state reaction. It crystallizes isotypically with the NaLnTiO(4) (Ln = La, Pr, Nd, Sm, Eu, Gd, Y and Lu) family. Five of the six atoms in the asymmetric unit (one K, one La, one Ti and two O atoms) are situated on sites with 4mm symmetry, whereas one O atom has 2mm. site symmetry. The crystal structure can b...

2011
Haiyan Chen Yixuan Zhang Yanling Lu

Nanoscale potassium niobate (KNbO3) powders of orthorhombic structure were synthesized using the sol-gel method. The heat-treatment temperature of the gels had a pronounced effect on KNbO3 particle size and morphology. Field emission scanning electron microscopy and transmission electron microscopy were used to determine particle size and morphology. The average KNbO3 grain size was estimated t...

2010
Igor V. Zatovsky Ivan V. Ogorodnyk Nataliya Yu. Strutynska Nikolay S. Slobodyanik Nataliya O. Sharkina

The title compound, K(0.8)Ca(9.8)Fe(0.2)(PO(4))(7) (potassium deca-calcium iron hepta-phosphate), belongs to the whitlockite family. The structure is built up from several types of metal-oxygen polyhedra: two [CaO(8)], one [CaO(7)] and one [(Ca/Fe)O(6)] polyhedron with a mixed Ca/Fe occupancy in a 0.8:0.2 ratio, as well as three tetra-hedral [PO(4)] units. Of the 18 sites in the asymmetric unit...

2013
S. Disch

Figure S1: X-ray powder diffraction pattern of the iron oxide nanospheres sample. X-ray Powder diffraction (XRPD) was measured on a conventional in-house powder diffractometer using Cu Kα radiation. Rietveld refinement yields cubic lattice parameters of 8.362(2) Å for the nanospheres and 8.348(1) Å for the nanocubes, which are both close to the cubic spinel lattice parameter of maghemite. The r...

Journal: :Chemical communications 2011
Sharon Lai-Fung Chan Kam-Hung Low Gary Kwok-Ming So Stephen Sin-Yin Chui Chi-Ming Che

Eight homoleptic metal(III) arylchalcogenolate polymers [M(EPh-p-X)(3)](n) (M = Ru, Cr, and Mo) were characterized by PXRD. Structural solution of [Ru(SPh-p-tBu)(3)](n)1 was achieved by Rietveld refinement of the PXRD data. Pyrolysis of [Ru(SePh)(3)](n)4 produced nanostructured RuSe(2), which selectively catalyzed the reduction of nitro compounds in the presence of other functionalities.

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