Rietveld refinement of the ranciéite structure using synchrotron powder diffraction data

2008 ◽  
Vol 23 (1) ◽  
pp. 10-14 ◽  
Author(s):  
Jeffrey E. Post ◽  
Peter J. Heaney ◽  
Andreas Ertl
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Octahedral Sheet ◽  
X Ray ◽  
Synchrotron Powder Diffraction ◽  
The Mean

Rietveld refinement using synchrotron powder X-ray diffraction data of the ranciéite, Ca0.19K0.01(Mn4+0.91◻0.09)O2⋅0.63H2O, crystal structure reveals significant differences from that reported previously. The interlayer H2O molecules occupy sites halfway between the Mn,O octahedral sheets. The Mn sites in the octahedral sheets have 10% vacancies, and the mean Mn–O distance indicates that all Mn is tetravalent (Mn4+). The interlayer Ca cations are located above and below the Mn vacancies and are octahedrally coordinated to three O2 atoms in the octahedral sheet and three H2O molecules in the interlayer.

Powder X-ray diffraction of levothyroxine sodium pentahydrate, C15H10I4NNaO4(H2O)5

2015 ◽  
Vol 30 (4) ◽  
pp. 370-371
Author(s):  
J.A. Kaduk ◽  
K. Zhong ◽  
T.N. Blanton ◽  
S. Gates ◽  
T.G. Fawcett
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Room Temperature ◽  
Levothyroxine Sodium ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Hydrogen Atoms ◽  
X Ray ◽  
Synchrotron Powder Diffraction

The room-temperature crystal structure of levothyroxine sodium pentahydrate has been refined using synchrotron powder diffraction data. The compound crystallizes in space group P1 (#1) with a = 8.2489(4), b = 9.4868(5), c = 15.8298(6) Å, α = 84.1387(4), β = 83.1560(3), γ = 85.0482(3) deg, V = 1220.071(9) Å3, and Z = 2. Hydrogen atoms (missing from the previously-reported structure) were included.

scholarly journals Synthesis and crystal structure of the quaternary semiconductor Cu2NiGeS4, a new stannite-type compound

2019 ◽  
Vol 65 (4 Jul-Aug) ◽  
pp. 355 ◽  
Author(s):  
G. E. Delgado ◽  
And V. Sagredo
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Quaternary Compound ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Cell Parameters

The crystal structure of the quaternary compound Cu2NiGeS4, belonging to the system I2-II-IV-VI4, was characterized by Rietveld refinement using X-ray powder diffraction data. This material crystallize with a stannite structure in the tetragonal space group I2m (Nº 121), Z = 2, unit cell parameters a = 5.3384(1) Å, c = 10.5732(3) Å, V = 301.32(3) Å3, acknowledged as a normal valence adamantane-structure.

Neutron Diffraction from Novel Materials

MRS Bulletin ◽  
1999 ◽  
Vol 24 (12) ◽  
pp. 24-28
Author(s):  
Paolo G. Radaelli ◽  
James D. Jorgensen
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Neutron Powder Diffraction ◽  
Inorganic Crystal Structure Database ◽  
Powder Diffraction Data ◽  
New Materials ◽  
X Ray

The discovery and development of new materials is the foundation of the science and technology “food chains.” Examples of new materials with novel properties that have stimulated new scientific questions and/or led to new technologies include liquid crystals, advanced batteries, structural ceramics, dielectrics, ferroelectrics, catalysts, high-temperature superconductors, har dmagnets, and magnetoresistive devices. Establishing the crystal structure of a newly discovered Compound is a mandatory first step, but the most important contribution of diffraction techniques is to provide an understanding of the relationships among chemical composition, crystal structure, and physical behavior. In this way, diffraction experiments provide critical Information for testing theories that explain novel behavior and guide the optimization of new materials to meet the demands of emerging technologies.The first samples of newly discovered materials are often polycrystalline. With state-of-the-art neutron powder diffraction data and Rietveld refinement techniques, for structures of modest complexity, the precision for atom positions rivals that obtained by single-crystal diffraction. Rietveld refinement is a method of obtaining accurate values for atom positions and other structural parameters from powder diffraction data by least-squares fitting of a calculated model to the full diffraction pattern. As evidence of thi s success, the Inorganic Crystal Structure Database contains 6044 entries from neutron powder diffraction, 7096 from laboratory x-ray powder diffraction, an d 228 from Synchrotron x-ray powder diffraction. Other reasons for the rapidly growing impact of neutron diffraction include the favorable neutron-scattering cross sections for light elements, the sensitivity to magnetic moments, and the ability to penetrate special sample environments for in situ studies. These strengths are widely accepted and have been exploited for many years. Previous reviews have focused on these topics.

X-ray powder diffraction data and Rietveld refinement of CrFe3NiSn5

2004 ◽  
Vol 19 (4) ◽  
pp. 372-374
Author(s):  
Jirong Huang ◽  
Lingmin Zeng ◽  
Zhihui Sun
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Type ◽  
Powder Diffraction Data ◽  
Hexagonal Crystal ◽  
X Ray ◽  
Crystal System ◽  
Power Pattern

X-ray power diffraction data for CrFe3NiSn5 are reported. Indexing the XRD power pattern and Rietveld refinement shows that the compound crystallizes in the hexagonal crystal system, space group P6mm (No. 183) with lattice parameters a=5.3168(1) Å, c=4.4261(1) Å, z=0.6 and Dcalc=8.011 g cm−3. The crystal structure of CrFe3NiSn5 is of the CoSn structure type with Fe, Cr and Ni disordered in the Co position.

scholarly journals Crystal structure of calcium perchlorate anhydrate, Ca(ClO4)2, from laboratory powder X-ray diffraction data

2018 ◽  
Vol 74 (4) ◽  
pp. 514-517 ◽  
Author(s):  
Dongmin Lee ◽  
Hyeri Bu ◽  
Dohwan Kim ◽  
Jooeun Hyoung ◽  
Seung-Tae Hong
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Wyckoff Position ◽  
Hydrated Calcium

The crystal structure of calcium perchlorate anhydrate was determined from laboratory X-ray powder diffraction data. The title compound was obtained by heating hydrated calcium perchlorate [Ca(ClO4)2·xH2O] at 623 K in air for 12 h. It crystallizes in the orthorhombic space group Pbca and is isotypic with Ca(AlD4)2. The asymmetric unit contains one Ca, two Cl and eight O sites, all on general sites (Wyckoff position 8c). The crystal structure consists of isolated ClO4 − tetrahedra and Ca2+ cations. The Ca2+ cation is coordinated by eight O atoms of eight symmetry-related ClO4 − tetrahedra within a distorted square-antiprismatic environment.

scholarly journals Rietveld Structure Refinement of the Stilbite Crystals from Deccan Traps (India) Using X-ray Powder Diffraction Data

2019 ◽  
Vol 70 (7) ◽  
pp. 2379-2384
Author(s):  
Gheorghe Branoiu ◽  
Ibrahim Ramadan
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Refinement ◽  
Deccan Traps ◽  
Western India ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Cell Parameters

The crystal structure of a spectacular sample of stilbite from Pune region located in the Deccan Traps (western India) has been refined using X-Ray powder diffraction data and the Rietveld method. The Rietveld refinement was carried out using the computer program Diffracplus TOPAS 4.1. The pseudo-Voigt (pV) profile function was used for the fit of the peaks. The Rietveld refinement of the analyzed sample in the space group C2/m (No.12): a=13.606 �, b=18.260 �, c=11.253 �, b=127.432�, Z=8, confirm the basic stilbite structure. The chemical composition of the stilbite crystals from Pune region (India) was determined by EDX analysis. The paper presents a new set of the unit cell parameters and fractional coordinates that define the stilbite crystal structure. The quality of the sample analyzed was pristine, the sample being collected from an association of apophyllite-stilbite crystals of centimetric dimensions.

scholarly journals Ab initio and DFT study on Cu (II) complex salicylate derivative

2014 ◽  
Vol 70 (a1) ◽  
pp. C1442-C1442
Author(s):  
Karthikeyan Natarajan ◽  
Sathya Duraisamy ◽  
Sivakumar Kandasamy
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray

X -ray diffraction becomes a routine process these decades for determining crystal structure of the materials. Most of the crystal structures solved nowadays is based on single crystal X-ray diffraction because it solves the crystal and molecular structures from small molecules to macro molecules without much human intervention. However it is difficult to grow single crystals of sufficient size and quality for conventional single-crystal X-ray diffraction studies. In such cases it becomes essential that structural information can be determined from powder diffraction data. With the recent developments in the direct-space approaches for structure solution, ab initio crystal structure analysis of molecular solids can be accomplished from X-ray powder diffraction data. It should be recalled that crystal structure determination from laboratory X-ray powder diffraction data is a far more difficult task than that of its single-crystal counterpart, particularly when the molecule possesses considerable flexibility or there are multiple molecules in the asymmetric unit. Salicylic acid and its derivatives used as an anti-inflammatory drug are known for its numerous medicinal applications. In our study, we synthesized mononuclear copper (II) complex of salicylate derivative. The structural characterization of the prepared compound was carried out using powder X-ray diffraction studies. Crystal structure of the compound has been solved by direct-space approach and refined by a combination of Rietveld method using TOPAS Academic V4.1. Density Functional Theory (DFT) calculations have to be carried in the solid state for the compound using GaussianW9.0 in the frame work of a generalized-gradient approximation (GGA). The geometry optimization was to be performed using B3LYP density functional theory. The atomic coordinates were taken from the final X-ray refinement cycle.

Crystallographic study of PtCl2(C2H3O2)2(C6H13N)(NH3) by Rietveld refinement

2003 ◽  
Vol 18 (2) ◽  
pp. 140-143 ◽  
Author(s):  
Lingmin Zeng ◽  
Liangwei Chen ◽  
Shaoping Pu ◽  
Yikun Yang ◽  
Wenggui Gao ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Anticancer Drug ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
Crystallographic Study

X-ray powder diffraction data for the anticancer drug PtCl2(C2H3O2)2(C6H13N)(NH3) are reported. The crystal structure of PtCl2(C2H3O2)2(C6H13N)(NH3) obtained from a Rietveld refinement are: space group P21/a, a=13.547(2) Å, b=8.260(1) Å, c=14.638(3) Å, β=110.429(2)°, V=1534.96 Å3, Z=4 and Dcalc.=2.068 Mg/m3.

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