Statistical Inference, Size Distributions and Peak Broadening in Finite Crystals

1987 ◽  
Vol 2 (4) ◽  
pp. 220-224 ◽  
Author(s):  
A. G. Alvarez ◽  
R. D. Bonetto ◽  
D. M. A. Guérin ◽  
A. Plastino ◽  
L. Rebollo Neira
Keyword(s):  
Information Theory ◽  
Statistical Inference ◽  
Diffraction Data ◽  
Crystal Size ◽  
The Other ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Size Distributions ◽  
Peak Broadening

AbstractCalculations of crystal size distributions in oriented clays (montmorillonite and kaolinite) are carried out utilizing X-ray diffraction data together with a method based on information theory. Two different procedures for dealing with the available data are compared. One of them involves some points of the corresponding spectrum, the other correlates the data by means of their moments.

scholarly journals Combining wavelets with statistical inference to map the mineralogical composition of pedological features from synchrotron X-ray diffraction data

2020 ◽  
Vol 2 (7) ◽  
Author(s):  
Claude Manté ◽  
Daniel Borschneck ◽  
Cristian Mocuta ◽  
Romain van den Bogaert ◽  
David Montagne ◽  
...  
Keyword(s):  
Statistical Inference ◽  
Diffraction Data ◽  
Mineralogical Composition ◽  
X Ray Diffraction ◽  
X Ray

The perchlorotriphenylmethyl (PTM) radical

2013 ◽  
Vol 69 (3) ◽  
pp. 255-257 ◽  
Author(s):  
Judith Guasch ◽  
Xavier Fontrodona ◽  
Imma Ratera ◽  
Concepció Rovira ◽  
Jaume Veciana
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Data ◽  
The Other ◽  
X Ray Diffraction ◽  
Monoclinic Symmetry ◽  
Steric Strain ◽  
High Chemical ◽  
X Ray ◽  
Cl Atoms

In spite of the considerable understanding and development of perchlorotriphenylmethyl (PTM) radical derivatives, the preparation of crystals of the pure unsubstituted PTM radical, C19Cl15, suitable for single-crystal X-ray diffraction has remained a challenge since its discovery, and only two studies dealing with the crystal structure of the unsubstituted PTM radical have been published. In one study, the radical forms clathrates with aromatic solvents [Veciana, Carilla, Miravitlles & Molins (1987).J. Chem. Soc. Chem. Commun.pp. 812–814], and in the other the structure was determinedab initiofrom powder X-ray diffraction data [Rius, Miravitlles, Molins, Crespo & Veciana (1990).Mol. Cryst. Liq. Cryst.187, 155–163]. We report here the preparation of PTM crystals for single-crystal X-ray diffraction and their resolution. The structure, which shows monoclinic symmetry (C2/c), revealed a nonsymmetric molecular propeller conformation (D3symmetry) caused by the steric strain between theortho-Cl atoms, which protect the central C atom (sp2-hybridization and major spin density) and give high chemical and thermal persistence to the PTM. The supramolecular structure of PTM shows short Cl...Cl intermolecular interactions and can be described in terms of layers formed by rows of molecules positioned in a head-to-tail manner along thecaxis.

scholarly journals A new fast method to derive crystallite size distributions (CSD) from 2D X-ray diffraction data.

2015 ◽  
Vol 71 (a1) ◽  
pp. s287-s288
Author(s):  
Sigmund H. Neher ◽  
Chaouachi Marwen ◽  
Falenty Andrzej ◽  
Klein Helmut ◽  
Werner F. Kuhs
Keyword(s):  
Crystallite Size ◽  
Diffraction Data ◽  
Fast Method ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
X Ray

Formamidinhim-Hexachloroferrat(III) Synthese und Kristallstruktur / Formamidinium-Hexachloroferrate(III) Synthesis and Crystal Structure

1985 ◽  
Vol 40 (3) ◽  
pp. 443-446 ◽  
Author(s):  
Udo Demant ◽  
Elke Conradi ◽  
Ulrich Müller ◽  
Kurt Dehnicke
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
The Other ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
Positional Disorder ◽  
Lattice Constants ◽  
Bond Lengths

[HC(NH2)2]3FeCl6 was obtained together with other products from the reaction of S4N4 with HCl in H2CCl2 in the presence of FeCl3. Its crystal structure was determined from X-ray diffraction data (473 independent observed reflexions, R = 0.047). Lattice constants: a = 961.6, c = 876.4 pm; tetragonal, space group P42/m, Z = 2. Of the two crystallographically independent formamidinium ions HC(NH2)2⊕, one exhibits positional disorder; the other one has C-N bond lengths of 128 pm. The FeCl63⊖ ions have symmetry C2h, but the deviation from Oh is small.

Refinement of d-AlNico Quasicrystal Structures

2000 ◽  
Vol 643 ◽  
Author(s):  
Hiroyuki Takakura ◽  
Akiji Yamamoto ◽  
An Pang Tsai
Keyword(s):  
Chemical Composition ◽  
High Resolution ◽  
Single Crystal ◽  
Diffraction Data ◽  
The Other ◽  
Structure Model ◽  
X Ray Diffraction ◽  
Data Set ◽  
X Ray ◽  
High Resolution Images

AbstractThe models of decagonal Al72Ni20Co8 quasicrystal with the space group of P105/mmc were refined on the basis of single crystal x-ray diffraction data set using the 5D description. The results of a structure model derived from Al13Fe4-type approximant crystal and Burkov model are compared. The former gives ω R=0.045 and R=0.063 for 449 reflections with 103 parameters and a resonable chemical composition of Al71.2TM28.8 (TM=transition metals). The projected structure in consistent with high resolution images of this material. On the other hand, the latter gives ωR=0.161 and R=0.193 for 55 parameters and a compositon of Al64.6TM35.1.

Lineshape Analysis of X-ray Diffraction Profiles: Polyethylene and Model Copolymers

1990 ◽  
Vol 34 ◽  
pp. 519-529
Author(s):  
Buckley Crist ◽  
Paul R. Howard
Keyword(s):  
Crystal Size ◽  
Lattice Parameter ◽  
Parameter Fluctuation ◽  
Line Profiles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lineshape Analysis ◽  
Small Peak ◽  
Peak Broadening ◽  
Diffraction Peaks

Studies of the shapes of X-ray diffraction peaks from synthetic polymers are still rather uncommon. One probable cause of this situation is the small peak-to-background ratio in most polymer diffraction experiments; it is difficult to achieve precise line profiles for quantitative analysis. Increased utilization of automated data collection/analysis systems and more intense X-ray sources should alleviate this restriction. We suspect, furthermore, that confusion about nomenclature has impeded the acceptance of lineshape analysis for polymers. The peak broadening mechanisms which are generally considered are finite coherence length or crystal size, lattice parameter fluctuation, and displacement disorder of the second kind. Both latter mechanisms have, unfortunately, been referred to as “strains” or “microstrains”. Metallurgists have traditionally expressed displacement disorder as a (length dependent) “microstrain”, and this convention has been adopted in some studies of polymer diffraction. Other work on polymers, however, has termed lattice parameter fluctuation as “microstrain“. The inconsistent use of this term can imply a nonexistent relation between two distinct phenomena.

Structural disorder of a new zeolite-like lithosilicate, K2.6Li5.4[Li4Si16O38]·4.3H2O

2006 ◽  
Vol 62 (1) ◽  
pp. 42-51 ◽  
Author(s):  
So-Hyun Park ◽  
Hans Boysen ◽  
John B. Parise
Keyword(s):  
Diffraction Data ◽  
Structural Disorder ◽  
The Other ◽  
Third Generation ◽  
Framework Structure ◽  
X Ray Diffraction ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Fibrous Zeolites ◽  
New Framework

The framework structure of the synthetic microporous lithosilicate RUB-30 (K2.6Li5.4[Li4Si16O38]·4.3H2O) is similar to that of the fibrous zeolites such as natrolite, edingtonite and thomsonite, since all their frameworks include the same secondary structural building unit, the so-called 4–1 T 5O10 cluster of tetrahedra. Unique to the structure of RUB-30, each 4–1 unit consists of a LiSi4O10 moiety within which the single [LiO4] tetrahedron is strictly segregated from the other four [SiO4] tetrahedra. The connection of neighboring 4–1 units through edge-sharing [LiO4] tetrahedra results in a new framework topology. The present work reports an `average' structure of RUB-30 solved by synchrotron X-ray single-crystal diffraction data collected at a second-generation source. A superstructure with a × 2b × c (relative to the subcell quoted above) could be seen in X-ray diffraction data collected with better resolution and higher brightness at a third generation source. Diffuse streaks along k with l = odd and unusual superstructure hkl reflections, with k = odd and l = odd only, indicate a more complicated real structure of the material. To explain this observation we propose two different structure types which are statistically, but coherently, intergrown in RUB-30.

Über zwei Modifikationen von "Tl2Cl3"-valenzgemischten Thallium(I)-hexahalogenothallaten(III) Tl3 [TlCl6] / On Two Modifications of "Tl2Cl3"-Mixed Valence Thallium(I)-hexahalogenothallates(III)

1980 ◽  
Vol 35 (11) ◽  
pp. 1366-1372 ◽  
Author(s):  
Reinhild Böhme ◽  
Jörg Rath ◽  
Bernd Grunwald ◽  
Gerhard Thiele
Keyword(s):  
Crystal Structure ◽  
Raman Spectra ◽  
Diffraction Data ◽  
Mixed Valence ◽  
Three Dimensional ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Thallium Chloride

The mixed valence thallium chloride "Tl2Cl3" is polymorphous. Raman spectra and comparable lattice translations suggest similar structures of both modifications. The crystal structure of the rhombic α-Tl2Cl3 crystallizing in yellow, needle-shaped crystals, has been determined from three-dimensional X-ray diffraction data. The unit cell with cell parameters a= 1474.8(5) pm, b - 2508.7(6) pm and c = 1267.6(2) pm contains 16 formula units distributed on 24 independent atom positions. The compound is a mixed valence thallium(I)-hexachlorothallate(III) Tl3[TlCl6] because three of the nine independent Tl atoms are surrounded octahedrally by CI atoms in distances of 250-265 pm, while the other Tl atoms have seven, eight or nine CI neighbours variing between 306 and 383 pm.β-Tl3[TlCl6] forms pale yellow thin platelets and crystallizes monoclinic with cell parameters a = 2549.4(13) pm, 6 = 1469.9(8) pm, c = 1308.5(12) pm and β = 108.58°.

scholarly journals Pirquitasite, Ag2ZnSnS4

2013 ◽  
Vol 69 (2) ◽  
pp. i8-i9 ◽  
Author(s):  
Benjamin N. Schumer ◽  
Robert T. Downs ◽  
Kenneth J. Domanik ◽  
Marcelo B Andrade ◽  
Marcus J. Origlieri
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
General Formula ◽  
Diffraction Data ◽  
The Other ◽  
Tetragonal Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Anisotropic Displacement Parameters

Pirquitasite, ideally Ag2ZnSnS4(disilver zinc tin tetrasulfide), exhibits tetragonal symmetry and is a member of the stannite group that has the general formulaA2BCX4, withA= Ag, Cu;B= Zn, Cd, Fe, Cu, Hg;C= Sn, Ge, Sb, As; andX= S, Se. In this study, single-crystal X-ray diffraction data are used to determine the structure of pirquitasite from a twinned crystal from the type locality, the Pirquitas deposit, Jujuy Province, Argentina, with anisotropic displacement parameters for all atoms, and a measured composition of (Ag1.87Cu0.13)(Zn0.61Fe0.36Cd0.03)SnS4. One Ag atom is located on Wyckoff site Wyckoff 2a(symmetry -4..), the other Ag atom is statistically disordered with minor amounts of Cu and is located on 2c(-4..), the (Zn, Fe, Cd) site on 2d(-4..), Sn on 2b(-4..), and S on general site 8g. This is the first determination of the crystal structure of pirquitasite, and our data indicate that the space group of pirquitasite isI-4, rather thanI-42mas previously suggested. The structure was refined under consideration of twinning by inversion [twin ratio of the components 0.91 (6):0.09 (6)].

Sign in / Sign up

Export Citation Format

Share Document