scholarly journals Evidence from x-ray and neutron powder diffraction patterns that the so-called icosahedral and decagonal quasicrystals of MnAl6 and other alloys are twinned cubic crystals

1987 ◽  
Vol 84 (12) ◽  
pp. 3951-3953 ◽  
Author(s):  
L. Pauling
Keyword(s):  
Powder Diffraction ◽  
Neutron Powder Diffraction ◽  
Cubic Crystals ◽  
X Ray ◽  
Decagonal Quasicrystals ◽  
Diffraction Patterns

Refinement of the Crystal Structures of Palladium-rich In-Pd Compounds by X-Ray and Neutron Powder Diffraction

2007 ◽  
Vol 62 (7) ◽  
pp. 929-934 ◽  
Author(s):  
Holger Kohlmanna ◽  
Clemens Ritter
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Structure Type ◽  
Neutron Powder Diffraction ◽  
Type Model ◽  
Rietveld Refinements ◽  
X Ray ◽  
Neutron Powder Diffraction Data ◽  
Diffraction Patterns ◽  
Catalyzed Reactions

Abstract The ternary indium palladium intermetallics In3Pd5, InPd2, and InPd3 have been synthesized by iodine-catalyzed reactions from the elements. Rietveld refinements on X-ray powder diffraction patterns provide the first accurate crystal structure data for In3Pd5 (Pbam, No. 55, a = 1104.20(2), b = 561.346(8), c = 424.263(6) pm, Rh5Ge3-type) and InPd2 (Pnma, No. 62, a = 561.676(6), b = 421.710(4), c = 822.78(8) pm, Co2Si-type). X-Ray powder diffraction apparently confirms the TiAl3 structure type proposed in the literature for InPd3. However, Rietveld refinement on neutron powder diffraction data reveals an In/Pd distributional disorder. Therefore, we describe the crystal structure of InPd3 in a AuCu-type model instead (P4/mmm, No. 123, a = 287.224(4), c = 380.079(7) pm), with mixed occupancy of one crystallographic site by 50% In and 50% Pd. In contrast to In3Pd5 and InPd2, which can be considered to be line compounds, InPd3 shows a non-negligible homogeneity range with unit cell volumes ranging from 0.126132(5) nm3 for the indium-rich to 0.125474(8) nm3 for the palladium-rich In1+xPd3−x phases. Mean In-Pd distances in these indium palladium intermetallics range from 272.3 pm (In1 in In3Pd5) with coordination number 8 for indium to 281.2 pm for 12-coordinated In in InPd3.

The Cambridge Crystallography Subroutine Library

1982 ◽  
Vol 15 (2) ◽  
pp. 167-173 ◽  
Author(s):  
J. C. Matthewman ◽  
P. Thompson ◽  
P. J. Brown
Keyword(s):  
Spin Density ◽  
Powder Diffraction ◽  
Neutron Powder Diffraction ◽  
X Ray ◽  
Density Maps ◽  
Recent Developments ◽  
Polarized Neutron ◽  
Diffraction Patterns ◽  
Nuclear Structures

The Cambridge Crystallography Subroutine Library (CCSL) is a versatile set of subroutines which will have many different applications for non-standard crystallography. At present it is used extensively at the Institut Laue–Langevin for interpreting all polarized neutron measurements, proceeding from the raw flipping-ratio measurements to the final production of spin-density maps. It is also used to analyse simple magnetic and more complicated nuclear structures, and for more general crystallographic applications such as arranging lists of reflections into groups of symmetry equivalents. It finds applications in the analysis of neutron powder diffraction patterns, as well as in more recent developments for the analysis of X-ray powder diffraction photographs.

scholarly journals “XANSONS for COD”: a new small BOINC project in crystallography

2018 ◽  
Vol 8 (1) ◽  
pp. 102-108
Author(s):  
Vladislav S. Neverov ◽  
Nikolay P. Khrapov
Keyword(s):  
Open Access ◽  
Internal Structure ◽  
Powder Diffraction ◽  
Open Source Software ◽  
Neutron Powder Diffraction ◽  
Nanocrystalline Phase ◽  
X Ray ◽  
Open Access Database ◽  
Diffraction Patterns ◽  
Crystallography Open Database

Abstract “XANSONS for COD” (http://xansons4cod.com) is a new BOINC project aimed at creating the open-access database of simulated x-ray and neutron powder diffraction patterns for nanocrystalline phase of materials from the collection of the Crystallography Open Database (COD). The project uses original open-source software XaNSoNS to simulate diffraction patterns on CPU and GPU. This paper describes the scientific problem this project solves, the project’s internal structure, its operation principles and organization of the final database.

Use of Neutron Diffraction for Describing Texture of Isostatically-Pressed Molybdite Powders

2005 ◽  
Vol 105 ◽  
pp. 83-88 ◽  
Author(s):  
H. Sitepu ◽  
Heinz Günter Brokmeier
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Powder Diffraction ◽  
Quantitative Description ◽  
Neutron Powder Diffraction ◽  
Powder Diffraction Data ◽  
Neutron Powder Diffraction Data ◽  
Pole Figures ◽  
Diffraction Patterns ◽  
Excellent Tool

The modelling and/or describing of texture (i.e. preferred crystallographic orientation (PO)) is of critical importance in powder diffraction analysis - for structural study and phase composition. In the present study, the GSAS Rietveld refinement with generalized spherical harmonic (GSH) was used for describing isostatically-pressed molybdite powders neutron powder diffraction data collected in the ILL D1A instrument. The results showed that for texture in a single ND data of molybdite the reasonable crystal structure parameters may be obtained when applying corrections to intensities using the GSH description. Furthermore, the WIMV method was used to extract the texture description directly from a simultaneous refinement with 1368 whole neutron diffraction patterns taken from the sample held in a variety of orientations in the ILL D1B texture goniometer. The results provided a quantitative description of the texture refined simultaneously with the crystal structure. Finally, the (002) molybdite pole-figures were measured using the GKSS TEX2 texture goniometer. The results showed that neutron diffraction is an excellent tool to investigate the texture in molybdite.

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