scholarly journals Rietveld and pair distribution function study of Hägg carbide using synchrotron X-ray diffraction

2011 ◽  
Vol 18 (2) ◽  
pp. 266-271 ◽  
Author(s):  
Hester Esna du Plessis ◽  
J. P. R. de Villiers ◽  
G. J. Kruger ◽  
A. Steuwer ◽  
M. Brunelli
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
X Ray Diffraction ◽  
X Ray ◽  
Function Study

scholarly journals Crystal Structure of Moganite and Its Anisotropic Atomic Displacement Parameters Determined by Synchrotron X-ray Diffraction and X-ray/Neutron Pair Distribution Function Analyses

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 272
Author(s):  
Seungyeol Lee ◽  
Huifang Xu ◽  
Hongwu Xu ◽  
Joerg Neuefeind
Keyword(s):  
Crystal Structure ◽  
Distribution Function ◽  
Single Crystal ◽  
Pair Distribution Function ◽  
Atomic Displacement ◽  
Single Crystal Xrd ◽  
X Ray Diffraction ◽  
X Ray ◽  
Neutron Pair ◽  
Atomic Displacement Parameters

The crystal structure of moganite from the Mogán formation on Gran Canaria has been re-investigated using high-resolution synchrotron X-ray diffraction (XRD) and X-ray/neutron pair distribution function (PDF) analyses. Our study for the first time reports the anisotropic atomic displacement parameters (ADPs) of a natural moganite. Rietveld analysis of synchrotron XRD data determined the crystal structure of moganite with the space group I2/a. The refined unit-cell parameters are a = 8.7363(8), b = 4.8688(5), c = 10.7203(9) Å, and β = 90.212(4)°. The ADPs of Si and O in moganite were obtained from X-ray and neutron PDF analyses. The shapes and orientations of the anisotropic ellipsoids determined from X-ray and neutron measurements are similar. The anisotropic ellipsoids for O extend along planes perpendicular to the Si-Si axis of corner-sharing SiO4 tetrahedra, suggesting precession-like movement. Neutron PDF result confirms the occurrence of OH over some of the tetrahedral sites. We postulate that moganite nanomineral is stable with respect to quartz in hypersaline water. The ADPs of moganite show a similar trend as those of quartz determined by single-crystal XRD. In short, the combined methods can provide high-quality structural parameters of moganite nanomineral, including its ADPs and extra OH position at the surface. This approach can be used as an alternative means for solving the structures of crystals that are not large enough for single-crystal XRD measurements, such as fine-grained and nanocrystalline minerals formed in various geological environments.

Temperature-dependent synchrotron X-ray diffraction, pair distribution function and susceptibility study on the layered compound CrTe3

2018 ◽  
Vol 233 (6) ◽  
pp. 361-370 ◽  
Author(s):  
Anna-Lena Hansen ◽  
Bastian Dietl ◽  
Martin Etter ◽  
Reinhard K. Kremer ◽  
David C. Johnson ◽  
...  
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Exchange Interactions ◽  
Structural Distortion ◽  
Layered Compound ◽  
Minor Amount ◽  
Zero Field ◽  
X Ray Diffraction ◽  
X Ray ◽  
Anisotropic Expansion

Abstract Results of combined synchrotron X-ray diffraction and pair distribution function experiments performed on the layered compound CrTe3 provide evidence for a short range structural distortion of one of the two crystallographically independent CrTe6 octahedra. The distortion is caused by higher mobility of one crystallographically distinct Te ion, leading to an unusual large Debye Waller factor. In situ high temperature X-ray diffraction investigations show an initial crystallization of a minor amount of elemental Te followed by decomposition of CrTe3 into Cr5Te8 and Te. Additional experiments provide evidence that the Te impurity (<1%) cannot be avoided. Analyses of structural changes in the temperature range 100–754 K show a pronounced anisotropic expansion of the lattice parameters. The differing behavior of the crystal axes is explained on the basis of structural distortions of the Cr4Te16 structural building units. An abrupt distortion of the structure occurs at T≈250 K, which then remains nearly constant down to 100 K. The structural distortion affects the spin exchange interactions between Cr3+ cations. A significant splitting between field-cooled (fc) and zero-field-cooled (zfc) magnetic susceptibility is observed below about 200 K. Applying a small external magnetic field results in a substantial spontaneous magnetization, reminiscent of ferro- or ferrimagnet exchange interactions below ~240 K. A Debye temperature of ~150 K was extracted from heat capacity measurements.

Thermal stability of Mg3Sb1.475Bi0.475Te0.05 high performance n-type thermoelectric investigated through powder X-ray diffraction and pair distribution function analysis

2018 ◽  
Vol 6 (35) ◽  
pp. 17171-17176 ◽  
Author(s):  
Lasse Rabøl Jørgensen ◽  
Jiawei Zhang ◽  
Christian Bonar Zeuthen ◽  
Bo Brummerstedt Iversen
Keyword(s):  
Thermal Stability ◽  
Distribution Function ◽  
Pair Distribution Function ◽  
High Performance ◽  
Function Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Stability Of

The thermal stability of the high performance n-type Te-doped Mg3Sb1.5Bi0.5 system is investigated.

THE ANALYSIS OF THE ATOMIC PAIR DISTRIBUTION FUNCTION OF PMN-BASED NANOPOWDERS BY X-RAY DIFFRACTION

2012 ◽  
Vol 26 (18) ◽  
pp. 1250118 ◽  
Author(s):  
M. GHASEMIFARD ◽  
GH. H. KHORRAMI
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Three Dimensional ◽  
Ferroelectric Material ◽  
Atomic Scale ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Pair Distribution Function ◽  
Atomic Pair ◽  
Perovskite Type

The three-dimensional atomic-scale structure around Mg , Nb , Ti and Zr atoms in a series ferroelectric material such as PMN, PZT, PMN-PZT and PMN-PT has been studied using X-ray diffraction ( MoK α), Rietveld refinement and the atomic pair distribution function (PDF) technique. The structure and particle size of the powders was determined by X-ray diffraction and TEM observation. The studies show that the materials are disordered at nanometer length distances. The three-dimensional atomic ordering in PMN-based nanopowders may well be described by a cubic structure of the perovskite type, similar to that occurring in the bulk crystals. At the end, the analyzed data show that the sizes of ZrO 6 octahedral are larger than TiO 6 octahedral.

Pair distribution function analysis of X-ray diffraction from amorphous spheres in an asymmetric transmission geometry: application to a Zr58.5Cu15.6Ni12.8Al10.3Nb2.8glass

2013 ◽  
Vol 46 (4) ◽  
pp. 999-1007 ◽  
Author(s):  
J. C. Bendert ◽  
N. A. Mauro ◽  
K. F. Kelton
Keyword(s):  
Distribution Function ◽  
Error Propagation ◽  
Pair Distribution Function ◽  
Function Analysis ◽  
X Ray Diffraction ◽  
Asymmetric Transmission ◽  
X Ray ◽  
Area Detector ◽  
Spherical Sample ◽  
Transmission Geometry

A method for the calculation of the pair distribution and structure functions from X-ray intensity data obtained with an area detector for an off-center incident X-ray beam on an amorphous sphere is presented. Error propagation for converting from the structure function to the pair distribution function is also described, including a summation series approach to treat the error from a high-qtruncation. A Zr58.5Cu15.6Ni12.8Al10.3Nb2.8glass (Vitreloy 106a) is used to demonstrate the techniques. In particular, the semi-analytical corrections presented to calculate the effects of secondary scatter within and asymmetric transmission through a spherical sample are verified.

scholarly journals Exploring the origins of crystallisation kinetics in hierarchical materials using in situ X-ray diffraction and pair distribution function analysis

2020 ◽  
Vol 22 (34) ◽  
pp. 18860-18867 ◽  
Author(s):  
Matthew E. Potter ◽  
Mark E. Light ◽  
Daniel J. M. Irving ◽  
Alice E. Oakley ◽  
Stephanie Chapman ◽  
...  
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Function Analysis ◽  
X Ray Diffraction ◽  
Crystallisation Kinetics ◽  
Total Scattering ◽  
Hierarchically Porous ◽  
X Ray ◽  
Scattering Measurements

Novel in situ synchrotron total scattering measurements probe the assembly of primary building units into templated hierarchically porous aluminophosphate catalysts, providing unique insights to understanding crystallisation kinetics.

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