2D X-ray diffraction and molecular modelling of the crystalline structure of polyesters under uniaxial stress

2021 ◽  
pp. 096739112199822
Author(s):  
Ahmed I Abou-Kandil ◽  
Gerhard Goldbeck
Keyword(s):  
Crystalline Structure ◽  
Molecular Modelling ◽  
Three Dimensional ◽  
Uniaxial Stress ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Modelling Techniques ◽  
Diffraction Patterns

Studying the crystalline structure of uniaxially and biaxially drawn polyesters is of great importance due to their wide range of applications. In this study, we shed some light on the behaviour of PET and PEN under uniaxial stress using experimental and molecular modelling techniques. Comparing experiment with modelling provides insights into polymer crystallisation with extended chains. Experimental x-ray diffraction patterns are reproduced by means of models of chains sliding along the c-axis leading to some loss of three-dimensional order, i.e. moving away from the condition of perfect register of the fully extended chains in triclinic crystals of both PET and PEN. This will help us understand the mechanism of polymer crystallisation under uniaxial stress and the appearance of mesophases in some cases as discussed herein.

Algorithms for the calculation of X-ray diffraction patterns from finite element data

2010 ◽  
Vol 43 (6) ◽  
pp. 1287-1299 ◽  
Author(s):  
E. Wintersberger ◽  
D. Kriegner ◽  
N. Hrauda ◽  
J. Stangl ◽  
G. Bauer
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Point Of View ◽  
X Ray Diffraction ◽  
Displacement Fields ◽  
X Ray ◽  
Si Substrates ◽  
Diffraction Patterns ◽  
Simulation Point ◽  
Ccd Detectors

A set of algorithms is presented for the calculation of X-ray diffraction patterns from strained nanostructures. Their development was triggered by novel developments in the recording of scattered intensity distributions as well as in simulation practice. The increasing use of two-dimensional CCD detectors in X-ray diffraction experiments, with which three-dimensional reciprocal-space maps can be recorded in a reasonably short time, requires efficient simulation programs to compute one-, two- and three-dimensional intensity distributions. From the simulation point of view, the finite element method (FEM) has become the standard tool for calculation of the strain and displacement fields in nanostructures. Therefore, X-ray diffraction simulation programs must be able to handle FEM data properly. The algorithms presented here make use of the deformation fields calculated on a mesh, which are directly imported into the calculation of diffraction patterns. To demonstrate the application of the developed algorithms, they were applied to several examples such as diffraction data from a dislocated quantum dot, from a periodic array of dislocations in a PbSe epilayer grown on a PbTe pseudosubstrate, and from ripple structures at the surface of SiGe layers deposited on miscut Si substrates.

scholarly journals Iron-containing phases in metallurgical and coke dusts as well as in bog iron ore

Nukleonika ◽  
2017 ◽  
Vol 62 (2) ◽  
pp. 187-195 ◽  
Author(s):  
Tadeusz Szumiata ◽  
Marzena Rachwał ◽  
Tadeusz Magiera ◽  
Katarzyna Brzózka ◽  
Małgorzata Gzik-Szumiata ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Spinel Structure ◽  
Iron Ore ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mineral Phases ◽  
Coke Plants ◽  
Wide Range ◽  
Specific Magnetic Susceptibility ◽  
Diffraction Patterns

Abstract Several samples of dusts from steel and coke plants (collected mostly with electro filters) were subjected to the investigation of content of mineral phases in their particles. Additionally, sample of bog iron ore and metallurgical slurry was studied. Next, the magnetic susceptibility of all the samples was determined, and investigations of iron-containing phases were performed using transmission Mössbauer spectrometry. The values of mass-specific magnetic susceptibility χ varied in a wide range: from 59 to above 7000 × 10−8 m-3·kg−1. The low values are determined for bog iron ore, metallurgical slurry, and coke dusts. The extremely high χ was obtained for metallurgical dusts. The Mössbauer spectra and X-ray diffraction patterns point to the presence of the following phases containing iron: hematite and oxidized magnetite (in coke and metallurgical dusts as well as metallurgical slurry), traces of magnetite fine grains fraction (in metallurgical dusts), amorphous glassy silicates with paramagnetic Fe3+ and Fe2+ ions, traces of pyrrhotite (in coke dusts), α-Fe and nonstoichiometric wüstite (in metallurgical slurry), as well as ferrihydrite nanoparticles (in bog iron ore). For individual samples of metallurgical dusts, the relative contributions of Fe2+/3+ ions in octahedral B sites and Fe2+ ions in tetrahedral A sites in magnetite spinel structure differs considerably.

Incorporating particle symmetry into orientation determination in single-particle imaging

2018 ◽  
Vol 74 (5) ◽  
pp. 512-517
Author(s):  
Miklós Tegze ◽  
Gábor Bortel
Keyword(s):  
Three Dimensional ◽  
Symmetric Case ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coherent Diffraction Imaging ◽  
Diffraction Imaging ◽  
Diffraction Patterns ◽  
Particle Imaging ◽  
Single Particle Imaging ◽  
Orientation Determination

In coherent-diffraction-imaging experiments X-ray diffraction patterns of identical particles are recorded. The particles are injected into the X-ray free-electron laser (XFEL) beam in random orientations. If the particle has symmetry, finding the orientation of a pattern can be ambiguous. With some modifications, the correlation-maximization method can find the relative orientations of the diffraction patterns for the case of symmetric particles as well. After convergence, the correlation maps show the symmetry of the particle and can be used to determine the symmetry elements and their orientations. The C factor, slightly modified for the symmetric case, can indicate the consistency of the assembled three-dimensional intensity distribution.

A complex pseudo-decagonal quasicrystal approximant, Al37(Co,Ni)15.5, solved by rotation electron diffraction

2014 ◽  
Vol 47 (1) ◽  
pp. 215-221 ◽  
Author(s):  
Devinder Singh ◽  
Yifeng Yun ◽  
Wei Wan ◽  
Benjamin Grushko ◽  
Xiaodong Zou ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Diffraction Data ◽  
Three Dimensional ◽  
Basic Structure ◽  
Electron Diffraction Data ◽  
Dimensional Electron ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

Electron diffraction is a complementary technique to single-crystal X-ray diffraction and powder X-ray diffraction for structure solution of unknown crystals. Crystals too small to be studied by single-crystal X-ray diffraction or too complex to be solved by powder X-ray diffraction can be studied by electron diffraction. The main drawbacks of electron diffraction have been the difficulties in collecting complete three-dimensional electron diffraction data by conventional electron diffraction methods and the very time-consuming data collection. In addition, the intensities of electron diffraction suffer from dynamical scattering. Recently, a new electron diffraction method, rotation electron diffraction (RED), was developed, which can overcome the drawbacks and reduce dynamical effects. A complete three-dimensional electron diffraction data set can be collected from a sub-micrometre-sized single crystal in less than 2 h. Here the RED method is applied forab initiostructure determination of an unknown complex intermetallic phase, the pseudo-decagonal (PD) quasicrystal approximant Al37.0(Co,Ni)15.5, denoted as PD2. RED shows that the crystal is F-centered, witha= 46.4,b= 64.6,c= 8.2 Å. However, as with other approximants in the PD series, the reflections with oddlindices are much weaker than those withleven, so it was decided to first solve the PD2 structure in the smaller, primitive unit cell. The basic structure of PD2 with unit-cell parametersa= 23.2,b= 32.3,c= 4.1 Å and space groupPnmmhas been solved in the present study. The structure withc= 8.2 Å will be taken up in the near future. The basic structure contains 55 unique atoms (17 Co/Ni and 38 Al) and is one of the most complex structures solved by electron diffraction. PD2 is built of characteristic 2 nm wheel clusters with fivefold rotational symmetry, which agrees with results from high-resolution electron microscopy images. Simulated electron diffraction patterns for the structure model are in good agreement with the experimental electron diffraction patterns obtained by RED.

Three-dimensional optical transforms

1961 ◽  
Vol 264 (1318) ◽  
pp. 339-354 ◽  
Keyword(s):  
Fourier Transforms ◽  
Three Dimensional ◽  
Polarized Light ◽  
Continuous Phase ◽  
Optical Diffraction ◽  
X Ray Diffraction ◽  
Circularly Polarized Light ◽  
X Ray ◽  
Half Wave ◽  
Diffraction Patterns

In recent years optical diffraction patterns have been used to assist in the solution of certain X-ray diffraction problems. The most useful technique—which is based partly on the properties of Fourier transforms and partly on optical experiments—is usually known as the optical-transform technique. It has, however, so far been confined to problems involving the projection of crystal structures on to a plane. The present work is aimed at extending the application to full three-dimensional structures. It is shown that this is most simply achieved by controlling the relative phases of beams of light; a method of phase control using circularly polarized light and half-wave plates of mica is described. The theory of the method, experimental details, and the demonstration of its validity are given. In order to gain experience in the use of three-dimensional optical transforms for solving X-ray diffraction problems a known structure has been examined, and the results of this work are included. Although this work has been primarily concerned with applications to X-ray diffraction, it is thought that the method of continuous phase changing, which is simple and linear, may find uses in other fields.

scholarly journals Femtosecond X-ray diffraction from two-dimensional protein crystals

IUCrJ ◽  
2014 ◽  
Vol 1 (2) ◽  
pp. 95-100 ◽  
Author(s):  
Matthias Frank ◽  
David B. Carlson ◽  
Mark S. Hunter ◽  
Garth J. Williams ◽  
Marc Messerschmidt ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Bragg Diffraction ◽  
Protein Crystal ◽  
Protein Crystals ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Linac Coherent Light Source ◽  
Diffraction Patterns ◽  
Better Than

X-ray diffraction patterns from two-dimensional (2-D) protein crystals obtained using femtosecond X-ray pulses from an X-ray free-electron laser (XFEL) are presented. To date, it has not been possible to acquire transmission X-ray diffraction patterns from individual 2-D protein crystals due to radiation damage. However, the intense and ultrafast pulses generated by an XFEL permit a new method of collecting diffraction data before the sample is destroyed. Utilizing a diffract-before-destroy approach at the Linac Coherent Light Source, Bragg diffraction was acquired to better than 8.5 Å resolution for two different 2-D protein crystal samples each less than 10 nm thick and maintained at room temperature. These proof-of-principle results show promise for structural analysis of both soluble and membrane proteins arranged as 2-D crystals without requiring cryogenic conditions or the formation of three-dimensional crystals.

A giant polymer lattice in a polymer-stabilized blue phase liquid crystal

Soft Matter ◽  
2015 ◽  
Vol 11 (23) ◽  
pp. 4572-4575 ◽  
Author(s):  
H. Kikuchi ◽  
S. Izena ◽  
H. Higuchi ◽  
Y. Okumura ◽  
K. Higashiguchi
Keyword(s):  
Liquid Crystal ◽  
Small Angle ◽  
Three Dimensional ◽  
Body Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phase Liquid ◽  
Blue Phase ◽  
Diffraction Patterns ◽  
Polymer Stabilized

Ultra-small angle X-ray diffraction patterns of a polymer-stabilized blue phase liquid crystal and a possible three-dimensional giant polymer lattice with body-centered cubic O8− symmetry formed in it.

scholarly journals Reconstructing three-dimensional protein crystal intensities from sparse unoriented two-axis X-ray diffraction patterns

2017 ◽  
Vol 50 (4) ◽  
pp. 985-993 ◽  
Author(s):  
Ti-Yen Lan ◽  
Jennifer L. Wierman ◽  
Mark W. Tate ◽  
Hugh T. Philipp ◽  
Veit Elser ◽  
...  
Keyword(s):  
Radiation Damage ◽  
Parallel Computation ◽  
Three Dimensional ◽  
Protein Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Small Crystals ◽  
Diffraction Patterns ◽  
Memory Scaling ◽  
Lysozyme Crystal

Recently, there has been a growing interest in adapting serial microcrystallography (SMX) experiments to existing storage ring (SR) sources. For very small crystals, however, radiation damage occurs before sufficient numbers of photons are diffracted to determine the orientation of the crystal. The challenge is to merge data from a large number of such `sparse' frames in order to measure the full reciprocal space intensity. To simulate sparse frames, a dataset was collected from a large lysozyme crystal illuminated by a dim X-ray source. The crystal was continuously rotated about two orthogonal axes to sample a subset of the rotation space. With the EMC algorithm [expand–maximize–compress; Loh & Elser (2009).Phys. Rev. E,80, 026705], it is shown that the diffracted intensity of the crystal can still be reconstructed even without knowledge of the orientation of the crystal in any sparse frame. Moreover, parallel computation implementations were designed to considerably improve the time and memory scaling of the algorithm. The results show that EMC-based SMX experiments should be feasible at SR sources.

Synthesis Of Highly Ordered Macroporous Minerals: Extension of the Synthetic Method to Other Metal Oxides and Organic-Inorganic Composites

1998 ◽  
Vol 549 ◽  
Author(s):  
C.F. Blanford ◽  
T.N. Do ◽  
B.T. Holland ◽  
A. Stein
Keyword(s):  
Electron Microscopy ◽  
Metal Oxides ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Wide Range ◽  
Ordered Macroporous ◽  
Lower Temperature

AbstractThe facile synthesis of three-dimensional macroporous arrays of titania, zirconia and alumina was recently reported [1]. The synthesis of these materials has now been extended to the oxides of iron, tungsten, and antimony, as well as a mixed yttrium-zirconium system and organically modi- fied silicates. These materials were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray energy dispersive spectrometry (EDS), and powder X-ray diffraction (XRD). Ordered structures of iron, tungsten, and antimony were formed from alkoxide precursors as in the originally reported synthesis, but the template was removed at a lower temperature. Samples of vinyl- and 2-cyanoethyl-modified silicates were formed from a mixture of organotrialkoxysilane and tetraalkoxysilane precursors; the polystyrene template was removed by extraction with a THF/acetone mixture. These results show the ease of extending the original syn- thesis to a wide range of systems. Also, the ability to form homogenous mixed-metal oxides will be important for tailoring the dielectric and photonic properties of these materials.

scholarly journals Single-crystal diffraction data from powder samples via SFX

2014 ◽  
Vol 70 (a1) ◽  
pp. C1449-C1449
Author(s):  
Tao Zhang ◽  
Shifeng Jin ◽  
Yuanxin Gu ◽  
Yao He ◽  
Haifu Fan
Keyword(s):  
Single Crystal ◽  
Diffraction Data ◽  
Three Dimensional ◽  
Monte Carlo Integration ◽  
X Ray Diffraction ◽  
Single Crystal Diffraction ◽  
Single Experiment ◽  
X Ray ◽  
Powder Samples ◽  
Diffraction Patterns

With the serial femtosecond crystallography (SFX) [1] using hard X-ray free-electron laser as light source, it is possible to obtained three-dimensional single-crystal diffraction data from powder samples consisting of submicron crystal grains. This offers two advantages. First, complicated crystal structures far beyond the ability of powder X-ray diffraction analysis now can be solved easily; second, mixtures of two or more crystalline components can be examined in a single experiment. The percentage of each component can be determined accurately and the crystal structure of them can be solved readily. Simulating calculations were performed with a mixture of two different kinds of zeolites. The program suite CrystFEL [2] was used for simulating SFX diffraction patterns, diffraction indexing and Monte-Carlo integration of diffraction intensities. The program suite SHELX [3] was used for structure determination. Satisfactory results have been obtained and will be discussed in detail.

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