Crystal Structure Analysis of Cu-Zr Alloys by Convergent Beam Diffraction

1981 ◽  
Vol 39 ◽  
pp. 354-355
Author(s):  
A. F. Marshall ◽  
J. W. Steeds ◽  
D. Bouchet ◽  
S. L. Shinde ◽  
R. G. Walmsley
Keyword(s):  
Crystal Structure ◽  
Point Group ◽  
Intermetallic Phase ◽  
Three Dimensional ◽  
Crystal Structure Analysis ◽  
Ion Milling ◽  
Composition And Structure ◽  
Unit Cells ◽  
Sputter Deposited ◽  
Convergent Beam

Convergent beam electron diffraction is a powerful technique for determining the crystal structure of a material in TEM. In this paper we have applied it to the study of the intermetallic phases in the Cu-rich end of the Cu-Zr system. These phases are highly ordered. Their composition and structure has been previously studied by microprobe and x-ray diffraction with sometimes conflicting results.The crystalline phases were obtained by annealing amorphous sputter-deposited Cu-Zr. Specimens were thinned for TEM by ion milling and observed in a Philips EM 400. Due to the large unit cells involved, a small convergence angle of diffraction was used; however, the three-dimensional lattice and symmetry information of convergent beam microdiffraction patterns is still present. The results are as follows:1) 21 at% Zr in Cu: annealed at 500°C for 5 hours. An intermetallic phase, Cu3.6Zr (21.7% Zr), space group P6/m has been proposed near this composition (2). The major phase of our annealed material was hexagonal with a point group determined as 6/m.

The first crystal structure of the peptidase domain of the U32 peptidase family

2015 ◽  
Vol 71 (12) ◽  
pp. 2505-2512 ◽  
Author(s):  
Magdalena Schacherl ◽  
Angelika A. M. Montada ◽  
Elena Brunstein ◽  
Ulrich Baumann
Keyword(s):  
Crystal Structure ◽  
Catalytic Mechanism ◽  
Quaternary Structure ◽  
Catalytic Domain ◽  
Three Dimensional ◽  
Zinc Ion ◽  
Crystal Structure Analysis ◽  
Dimensional Structure ◽  
Sequence Motifs ◽  
Conserved Sequence

The U32 family is a collection of over 2500 annotated peptidases in the MEROPS database with unknown catalytic mechanism. They mainly occur in bacteria and archaea, but a few representatives have also been identified in eukarya. Many of the U32 members have been linked to pathogenicity, such as proteins fromHelicobacterandSalmonella. The first crystal structure analysis of a U32 catalytic domain fromMethanopyrus kandleri(genemk0906) reveals a modified (βα)8TIM-barrel fold with some unique features. The connecting segment between strands β7 and β8 is extended and helix α7 is located on top of the C-terminal end of the barrel body. The protein exhibits a dimeric quaternary structure in which a zinc ion is symmetrically bound by histidine and cysteine side chains from both monomers. These residues reside in conserved sequence motifs. No typical proteolytic motifs are discernible in the three-dimensional structure, and biochemical assays failed to demonstrate proteolytic activity. A tunnel in which an acetate ion is bound is located in the C-terminal part of the β-barrel. Two hydrophobic grooves lead to a tunnel at the C-terminal end of the barrel in which an acetate ion is bound. One of the grooves binds to aStrep-Tag II of another dimer in the crystal lattice. Thus, these grooves may be binding sites for hydrophobic peptides or other ligands.

The phase problem and electron-density maps

2010 ◽  
Author(s):  
Jenny Pickworth Glusker ◽  
Kenneth N. Trueblood
Keyword(s):  
Crystal Structure ◽  
Fourier Series ◽  
Diffraction Pattern ◽  
Electron Density ◽  
Bragg Reflection ◽  
Three Dimensional ◽  
Density Maps ◽  
Structure Factors ◽  
Unit Cells ◽  
Phase Angles

In order to obtain an image of the material that has scattered X rays and given a diffraction pattern, which is the aim of these studies, one must perform a three-dimensional Fourier summation. The theorem of Jean Baptiste Joseph Fourier, a French mathematician and physicist, states that a continuous, periodic function can be represented by the summation of cosine and sine terms (Fourier, 1822). Such a set of terms, described as a Fourier series, can be used in diffraction analysis because the electron density in a crystal is a periodic distribution of scattering matter formed by the regular packing of approximately identical unit cells. The Fourier series that is used provides an equation that describes the electron density in the crystal under study. Each atom contains electrons; the higher its atomic number the greater the number of electrons in its nucleus, and therefore the higher its peak in an electrondensity map.We showed in Chapter 5 how a structure factor amplitude, |F (hkl)|, the measurable quantity in the X-ray diffraction pattern, can be determined if the arrangement of atoms in the crystal structure is known (Sommerfeld, 1921). Now we will show how we can calculate the electron density in a crystal structure if data on the structure factors, including their relative phase angles, are available. The Fourier series is described as a “synthesis” when it involves structure amplitudes and relative phases and builds up a picture of the electron density in the crystal. By contrast, a “Fourier analysis” leads to the components that make up this series. The term “relative” is used here because the phase of a Bragg reflection is described relative to that of an imaginary wave diffracted in the same direction at a chosen origin of the unit cell.

A fourfold interpenetrating diamond-like three-dimensional zinc(II) coordination polymer: synthesis, crystal structure and physical properties

2019 ◽  
Vol 75 (5) ◽  
pp. 504-507 ◽  
Author(s):  
Hui-Ru Chen
Keyword(s):  
Crystal Structure ◽  
Room Temperature ◽  
Three Dimensional ◽  
Fluorescence Emission ◽  
Crystal Structure Analysis ◽  
The Novel ◽  
X Ray Diffraction ◽  
Metal Compounds ◽  
X Ray ◽  
Coordination Framework

Excellent fluorescence properties are exhibited by d 10 metal compounds. The novel three-dimensional ZnII coordination framework, poly[[{μ2-bis[4-(2-methyl-1H-imidazol-1-yl)phenyl] ether-κ2 N 3:N 3′}(μ2-furan-2,5-dicarboxylato-κ2 O 2:O 5)zinc(II)] 1.76-hydrate], {[Zn(C6H2O5)(C20H18N4O)]·1.76H2O} n , has been prepared and characterized using IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. The crystal structure analysis revealed that the compound exhibits a novel fourfold interpenetrating diamond-like network. This polymer also displays a strong fluorescence emission in the solid state at room temperature.

Diffuse scattering and short-range order in uranium iodine phthalocyanine [U1−x Pc2]I2−y and the X-ray structure analysis of crystals with diffuse superstructure reflections

2003 ◽  
Vol 59 (3) ◽  
pp. 384-392 ◽  
Author(s):  
J. Krawczyk ◽  
A. Pietraszko ◽  
R. Kubiak ◽  
K. Łukaszewicz
Keyword(s):  
Crystal Structure ◽  
Structure Analysis ◽  
Diffuse Scattering ◽  
Short Range ◽  
Short Range Order ◽  
Crystal Structure Analysis ◽  
Range Order ◽  
Small Range ◽  
X Ray ◽  
Unit Cells

Crystals of uranium iodine phthalocyanine present an example of a disordered commensurate modulated structure of the intergrowth type. The short-range order of both uranium ions and iodine chains [I_3^-] n has been analysed by Reverse Monte Carlo (RMC) simulation of X-ray diffuse scattering. The diffraction pattern of uranium iodine phthalocyanine contains diffuse superstructure reflections. In the routine crystal structure analysis diffuse superstructure reflections may be either omitted or measured and classified along with other Bragg reflections. The crystal structure of uranium iodine phthalocyanine is an example of such ambiguity. The crystal structures of two specimens of [U1−x Pc2]I2−y with slightly different composition have been published in the literature with different space groups and unit cells. We have shown that the structure of both specimens differs only in the degree of short-range order and is isostructural with [YbPc2]I2. We have also shown that while the omission of diffuse reflections results in the average crystal structure, the treatment of these reflections as normal Bragg reflections is incorrect and produces the structure averaged over a limited small range.

scholarly journals Crystal structure of the coordination polymer [FeIII2{PtII(CN)4}3]

2015 ◽  
Vol 71 (1) ◽  
pp. i1-i2
Author(s):  
Maksym Seredyuk ◽  
M. Carmen Muñoz ◽  
José A. Real ◽  
Turganbay S. Iskenderov
Keyword(s):  
Crystal Structure ◽  
Coordination Polymer ◽  
Point Group ◽  
Three Dimensional ◽  
Title Complex ◽  
Group Symmetry ◽  
Point Group Symmetry ◽  
Rotation Axes ◽  
Square Planar ◽  
Cyanide Ligands

The title complex, poly[dodeca-μ-cyanido-diiron(III)triplatinum(II)], [FeIII2{PtII(CN)4}3], has a three-dimensional polymeric structure. It is built-up from square-planar [PtII(CN)4]2−anions (point group symmetry 2/m) bridging cationic [FeIIIPtII(CN)4]+∞layers extending in thebcplane. The FeIIatoms of the layers are located on inversion centres and exhibit an octahedral coordination sphere defined by six N atoms of cyanide ligands, while the PtIIatoms are located on twofold rotation axes and are surrounded by four C atoms of the cyanide ligands in a square-planar coordination. The geometrical preferences of the two cations for octahedral and square-planar coordination, respectively, lead to a corrugated organisation of the layers. The distance between neighbouring [FeIIIPtII(CN)4]+∞layers corresponds to the lengtha/2 = 8.0070 (3) Å, and the separation between two neighbouring PtIIatoms of the bridging [PtII(CN)4]2−groups corresponds to the length of thecaxis [7.5720 (2) Å]. The structure is porous with accessible voids of 390 Å3per unit cell.

scholarly journals Crystal structure of langbeinite-related Rb0.743K0.845Co0.293Ti1.707(PO4)3

2015 ◽  
Vol 71 (3) ◽  
pp. 251-253 ◽  
Author(s):  
Nataliia Yu. Strutynska ◽  
Marina A. Bondarenko ◽  
Ivan V. Ogorodnyk ◽  
Vyacheslav N. Baumer ◽  
Nikolay S. Slobodyanik
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Point Group ◽  
Three Dimensional ◽  
Type Structure ◽  
Group Symmetry ◽  
Site Symmetry ◽  
Point Group Symmetry ◽  
Crystallization Method ◽  
Temperature Crystallization

Potassium rubidium cobalt(II)/titanium(IV) tris(orthophosphate), Rb0.743K0.845Co0.293Ti1.707(PO4)3, has been obtained using a high-temperature crystallization method. The obtained compound has a langbeinite-type structure. The three-dimensional framework is built up from mixed-occupied (Co/TiIV)O6octahedra (point group symmetry .3.) and PO4tetrahedra. The K+and Rb+cations are statistically distributed over two distinct sites (both with site symmetry .3.) in the large cavities of the framework. They are surrounded by 12 O atoms.

The stereochemistry of B -diketo complexes with trim ethylplatinum iv II. The crystal structure of ethyl(trim ethylplatini-)- acetoacetate

1960 ◽  
Vol 254 (1277) ◽  
pp. 218-228 ◽  
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Carbonyl Oxygen ◽  
Crystal Structure Analysis ◽  
Methyl Groups ◽  
Methylene Carbon ◽  
X Ray ◽  
Methylene Carbon Atom ◽  
Critical Account ◽  
Active Methylene

A three-dimensional X-ray crystal structure analysis of the complex between trimethyl platinum and ethylacetoacetate, (CH 3 ) 3 Pt CH 3 . CO. CH. CO OC 2 H 5 , has shown that the molecule is dimeric. In a monoclinic unit cell (a = 8.83, b = 14.12, c = 9.30 Å, β = 95°, space group P2 1 / c ) there are two centrosymmetrical dimeric molecules in which each platinum atom is octahedrally co-ordinated by three methyl groups, in the cis configuration, by the two carbonyl oxygen atoms of one β -ketoester and by the central, or ‘active methylene’ carbon atom of the other β -ketoester in the dimer. The structure is thus essentially the same as that of trimethyl 4:6-dioxononyl platinum (part I) and the result shows that complex formation via a tridentate β -diketo system is preferred to co-ordination through an ester oxygen. A critical account is given of the criteria used to judge the correctness of the results.

Nanoscopic unequivocal analysis of twinned crystal structures with tetragonal or orthogonal unit cells by electron microdiffraction

1999 ◽  
Vol 32 (3) ◽  
pp. 397-403 ◽  
Author(s):  
M. Leicht ◽  
T. Remmele ◽  
D. Stenkamp ◽  
H. P. Strunk
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Lattice Parameters ◽  
Transmission Electron ◽  
Unit Cells ◽  
Convergent Beam ◽  
Chalcogenide Compound ◽  
Habit Planes ◽  
Twinned Crystal Structure ◽  
Electron Microdiffraction

In this study, a particular type of nanoscopic twinned crystal structure which can occur in any tetragonal or orthogonal crystal structure with a ratio of lattice parameters c/a=c/b=2 is presented. This type of twinning is characterized by twin components whosecaxes are oriented perpendicular to one another, by twin-habit planes parallel to {102} planes, and by a superstructure along the twin boundaries which is described by orthogonal unit cells with lattice parameters 2a, 2a,a. Furthermore, the suitability of electron microdiffraction, a diffraction technique of transmission electron microscopy (TEM) with a moderately convergent beam, for the analysis of such twinned crystal structures is demonstrated. For this demonstration, electron microdiffraction is applied to the chalcogenide compound Cu2In3Se5, which indeed exhibits the proposed twinned crystal structure.

scholarly journals IPR Beamline for Macromolecular Assemblies at SPring-8 (BL44XU)

2014 ◽  
Vol 70 (a1) ◽  
pp. C1684-C1684
Author(s):  
Eiki Yamashita ◽  
Akifumi Higashiura ◽  
Masato Yoshimura ◽  
Kazuya Hasegawa ◽  
Yukito Furukawa ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Analysis ◽  
Diffraction Data ◽  
High Speed ◽  
Protein Crystallography ◽  
Three Dimensional ◽  
Crystal Structure Analysis ◽  
Standard Type ◽  
Double Crystal ◽  
Macromolecular Assemblies

Biological macromolecular assemblies play significant roles in many biological reaction systems, including energy transfer, protein synthesis, protein degradation and signal transduction. A detailed understanding of the functions of the macromolecular assemblies requires information derived from three-dimensional atomic structures. X-ray crystal structure analysis is one of the most powerful methods to determine the three-dimensional structures of macromolecular assemblies at atomic level. Since features of crystals of biological macromolecular assemblies are extremely weak diffraction power and narrow space between the diffraction spots, it is essential to use high brilliance and high paralleled synchrotron radiation for diffraction data collection from crystals of biological macromolecular assemblies. The Institute for Protein Research (IPR) of Osaka University is operating a beamline for crystal structure analysis of biological macromolecular assemblies at SPring-8 (BL44XU). This beamline is designed to collect high quality diffraction data from biological macromolecular assembly crystals with large unit cells. The light source of this beamline is a SPring-8 standard type in-vacuum undulator. Liquid nitrogen cooled double crystal monochromator and horizontal focusing mirror are used as the optical components. BSS (Beamline Scheduling Software), which is SPring-8 protein crystallography beamline standard GUI, is installed to unify user operation throughout protein crystallography beamlines in the SPring-8. We have recently upgraded to a high speed air-bearing goniostat and installed a high performance CCD detector, MX-300HE. Present status and future plan of the beamline will be presented.

The new P-chalcopyrite compound Cu2FeIn2Se5; synthesis, thermal analysis (DTA), and crystal structure analysis by X-ray powder diffraction (XRPD)

2021 ◽  
Vol 67 (1 Jan-Feb) ◽  
pp. 18
Author(s):  
G. E. Delgado ◽  
P. Grima-Gallardo ◽  
J. A. Aitken ◽  
A. Cárdenas ◽  
I. Brito
Keyword(s):  
Crystal Structure ◽  
Thermal Analysis ◽  
Three Dimensional ◽  
Crystal Structure Analysis ◽  
Chalcopyrite Structure ◽  
Distribution Analysis ◽  
X Ray Diffraction ◽  
Quaternary Compound ◽  
X Ray ◽  
Cell Parameters

The Cu2FeIn2Se5 alloy, belonging to the system (CuInSe2)1-x(FeSe)x with x= ⅓, was synthesized by the melt and annealing technique. The differential thermal analysis (DTA) indicates that this compound melts at 1017 K. The crystal structure of this new quaternary compound was established using powder X-ray diffraction. Cation distribution analysis indicates that this material crystallizes in a P-chalcopyrite structure, space group P2c (Nº 112), with unit cell parameters a = 6.1852(2) Å, c = 12.3633(9) Å, V = 472.98(4) Å3. Cu2FeIn2Se5 is a new adamantane type compound derivative of the sphalerite structure, and consists of a three-dimensional arrangement of distorted CuSe4, FeSe4, and InSe4 tetrahedral connected by common faces.

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