X-ray and neutron Rietveld quantitative phase analysis of industrial Portland cement clinkers

2004 ◽  
Vol 19 (3) ◽  
pp. 232-239 ◽  
Author(s):  
O. Pritula ◽  
Ľ. Smrčok ◽  
D. M. Többens ◽  
V. Langer
Keyword(s):  
High Resolution ◽  
Diffraction Data ◽  
Structural Data ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
X Ray ◽  
Numerical Instabilities ◽  
Cement Clinkers ◽  
Good Agreement

Weight fractions of four dominant phases (C3S, C2S, C4AF, and C3A) present in five industrial clinkers were estimated by a series of neutron and X-ray Rietveld refinements. Calculated powder patterns were derived from the structural data for monoclinic and triclinic C3S, monoclinic C2S, orthorhombic C4AF, cubic C3A and MgO. Neutron diffraction data were collected with the high resolution E9 diffractometer (BENSC) using two different wavelengths, X-ray diffraction data with a high resolution transmission diffractometer. Elemental composition of the samples obtained by ESEM/EDX technique were in a good agreement with the data delivered by the producers. Convergence of the refinements was remarkably different for X-ray and for neutron data. Several refinements were not completed due to numerical instabilities. Neutron refinements were found to be more stable than X-ray, but there was not any notable difference in the final estimated phases’ compositions. Calculated absolute deviates of phases’ weight fractions were mostly within ±10%, which for the less abundant phases corresponded to relative deviations within ±50%. © 2004 International Centre for Diffraction Data.

On reproducibility of Rietveld analysis of reference Portland cement clinkers

2003 ◽  
Vol 18 (1) ◽  
pp. 16-22 ◽  
Author(s):  
O. Pritula ◽  
Lˇ. Smrcˇok ◽  
B. Baumgartner
Keyword(s):  
Reference Values ◽  
Structural Data ◽  
Rietveld Analysis ◽  
Data Sets ◽  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
X Ray ◽  
Numerical Instabilities ◽  
Relative Errors ◽  
Cement Clinkers

Weight fractions of four dominant phases (C3S, C2S, C4AF and C3A) present in the NIST Reference Portland clinkers 8486, 8487 and 8488 were estimated by a series of Rietveld refinements. Calculated powder patterns were derived from the structural data for monoclinic C3S and C2S, orthorhombic C4AF and cubic C3A. X-ray diffraction data were collected in two laboratories with two diffractometers, a reflection and a transmission one. There were no significant differences between the results of the refinements based on the data sets collected on the machines with different experimental arrangements. Estimated phase compositions were compared to the reference values found by optical microscopy (MPC). Median agreement between refined and reference values within ±5% (absolute) was found only for 8488 clinker; for 8486 and C3A-rich 8487 it was within ±10% (absolute). In the majority of the refinements numerical instabilities were detected, leading to large correlations between FWHM and temperature parameters of some phases. The results obtained for C4AF were probably influenced by the presence of possible solid solutions with the structures close to that of C4AF. Weight fractions of low abundant C3A were estimated with the largest relative errors reaching in several cases ∼100%.

Tubulin structure at intermediate resolution

1995 ◽  
Vol 53 ◽  
pp. 852-853
Author(s):  
K. H. Downing ◽  
S. G. Wolf ◽  
E. Nogales
Keyword(s):  
High Resolution ◽  
Structural Data ◽  
Therapeutic Drug ◽  
Zinc Ions ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Negative Stain ◽  
Functional Mechanisms ◽  
Tubulin Structure

Microtubules are involved in a host of critical cell activities, many of which involve transport of organelles through the cell. Different sets of microtubules appear to form during the cell cycle for different functions. Knowledge of the structure of tubulin will be necessary in order to understand the various functional mechanisms of microtubule assemble, disassembly, and interaction with other molecules, but tubulin has so far resisted crystallization for x-ray diffraction studies. Fortuitously, in the presence of zinc ions, tubulin also forms two-dimensional, crystalline sheets that are ideally suited for study by electron microscopy. We have refined procedures for forming the sheets and preparing them for EM, and have been able to obtain high-resolution structural data that sheds light on the formation and stabilization of microtubules, and even the interaction with a therapeutic drug.Tubulin sheets had been extensively studied in negative stain, demonstrating that the same protofilament structure was formed in the sheets and microtubules. For high resolution studies, we have found that the sheets embedded in either glucose or tannin diffract to around 3 Å.

Investigation of Residual Strains of the Second Kind in Plastically Deformed Metallic Materials

1994 ◽  
Vol 376 ◽  
Author(s):  
M. Vrána ◽  
P. Klimanek ◽  
T. Kschidock ◽  
P. Lukáš ◽  
P. Mikula
Keyword(s):  
High Resolution ◽  
Neutron Diffraction ◽  
Stacking Faults ◽  
Metallic Materials ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
X Ray ◽  
Neutron Diffractometer ◽  
Residual Strains ◽  
Good Agreement

ABSTRACTInvestigation of strongly distorted crystal structures caused by dislocations, stacking-faults etc. in both plastically deformed f.c.c. and b.c.c. metallic materials was performed by the analysis of the neutron diffraction line broadening. Measurements were realized by means of the high resolution triple-axis neutron diffractometer equipped by bent Si perfect crystals as monochromator and analyzer at the NPI Řež. The substructure parameters obtained in this manner are in good agreement with the results of X-ray diffraction analysis.

D-67 High-Resolution X-ray Diffraction Data Analysis From The Partly Relaxed Semiconductor Structures

2009 ◽  
Vol 24 (2) ◽  
pp. 171-171
Author(s):  
A. Ulyanenkov ◽  
A. Benediktovitch ◽  
I. Feranchuk ◽  
B. He ◽  
H. Ress
Keyword(s):  
Data Analysis ◽  
High Resolution ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Semiconductor Structures

Revisit of α-Chitin Crystal Structure Using High Resolution X-ray Diffraction Data

2009 ◽  
Vol 10 (5) ◽  
pp. 1100-1105 ◽  
Author(s):  
Pawel Sikorski ◽  
Ritsuko Hori ◽  
Masahisa Wada
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Neutron and high-resolution room-temperature X-ray data collection from crystallized lytic polysaccharide monooxygenase

2015 ◽  
Vol 71 (11) ◽  
pp. 1448-1452 ◽  
Author(s):  
John-Paul Bacik ◽  
Sophanit Mekasha ◽  
Zarah Forsberg ◽  
Andrey Kovalevsky ◽  
Jay C. Nix ◽  
...  
Keyword(s):  
High Resolution ◽  
Diffraction Data ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Lytic Polysaccharide Monooxygenase ◽  
Data Set ◽  
X Ray ◽  
Processing Enzymes ◽  
Bacteria And Fungi ◽  
Polysaccharide Monooxygenase

Bacteria and fungi express lytic polysaccharide monooxgyenase (LPMO) enzymes that act in conjunction with canonical hydrolytic sugar-processing enzymes to rapidly convert polysaccharides such as chitin, cellulose and starch to single monosaccharide products. In order to gain a better understanding of the structure and oxidative mechanism of these enzymes, large crystals (1–3 mm3) of a chitin-processing LPMO from the Gram-positive soil bacteriumJonesia denitrificanswere grown and screened for their ability to diffract neutrons. In addition to the collection of neutron diffraction data, which were processed to 2.1 Å resolution, a high-resolution room-temperature X-ray diffraction data set was collected and processed to 1.1 Å resolution in space groupP212121. To our knowledge, this work marks the first successful neutron crystallographic experiment on an LPMO. Joint X-ray/neutron refinement of the resulting data will reveal new details of the structure and mechanism of this recently discovered class of enzymes.

Charge Densities and Electrostatic Potentials for Energetic Materials

1995 ◽  
Vol 418 ◽  
Author(s):  
A. A. Pinkerton ◽  
A. Martin
Keyword(s):  
High Resolution ◽  
Low Temperature ◽  
Diffraction Data ◽  
Energetic Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Charge Densities ◽  
Contour Maps ◽  
Deformation Density ◽  
Dinitramide Salts

AbstractHigh resolution (sinθ/λ < 1.34 Å−1), low temperature (85 K) X-ray diffraction data has been used to map the deformation density and the derived electrostatic potential for three dinitramide salts. The traditional presentation of contour maps has been replaced with 3D views of the molecule. A comparison of the dinitramide ions from each salt is presented.

Characterizing the Image Forming Particles of Modern Ungilded Daguerreotypes Using XRD and SEM

2019 ◽  
Vol 25 (4) ◽  
pp. 1037-1051
Author(s):  
Patrick Ravines ◽  
Alexander Y. Nazarenko
Keyword(s):  
High Resolution ◽  
Diffraction Data ◽  
Regions Of Interest ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Cubic Crystals ◽  
X Ray ◽  
Silver Amalgam ◽  
Crystalline Nature ◽  
Scanning Electron

AbstractX-ray diffraction (XRD) and high-resolution scanning electron microscopy (SEM) have been used to characterize the silver mercury amalgam particles resting on the surface that comprise the image of five daguerreotype plates that were not gilded and that were prepared by three different contemporary daguerreotype makers. The regions of interest of the surface that were examined were overexposed, solarized, and highlight (white) areas. The XRD portion of the study shows that the two main silver mercury amalgam particles identified using the International Center for Diffraction Data PF4 + database were the Schachnerite/ζ (zeta) phase amalgam, Ag1.1Hg0.9, and the mercury silver amalgam, Ag0.65Hg0.35. On one of the daguerreotypes a third silver mercury amalgam, Moschellandsbergite, Ag2Hg3, was also identified in small concentrations. High-resolution SEM images corroborate the diffraction data and show that the crystalline nature of the silver mercury amalgam particles on all five plates to be mostly hexagonal, which would correspond to the Schachnerite/ζ (zeta) phase amalgam, and fewer rectangular solid and cubic crystals corresponding to the mercury silver amalgam.

Crystal-structure analysis of four mineral samples of anhydrite, CaSO4, using synchrotron high-resolution powder X-ray diffraction data

2011 ◽  
Vol 26 (4) ◽  
pp. 326-330 ◽  
Author(s):  
Sytle M. Antao
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Unit Cell Volume ◽  
Crystal Structure Analysis ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Rietveld Refinements ◽  
X Ray ◽  
Cell Parameters

The crystal structures of four samples of anhydrite, CaSO4, were obtained by Rietveld refinements using synchrotron high-resolution powder X-ray diffraction (HRPXRD) data and space group Amma. As an example, for one sample of anhydrite from Hants County, Nova Scotia, the unit-cell parameters are a = 7.00032(2), b = 6.99234(1), c = 6.24097(1) Å, and V = 305.487(1) Å3 with a > b. The eight-coordinated Ca atom has an average <Ca-O> distance of 2.4667(4) Å. The tetrahedral SO4 group has two independent S-O distances of 1.484(1) to O1 and 1.478(1) Å to O2 and an average <S-O> distance of 1.4810(5) Å. The three independent O-S-O angles [108.99(8) × 1, 110.38(3) × 4, 106.34(9)° × 1; average <O-S-O> [6] = 109.47(2)°] and S-O distances indicate that the geometry of the SO4 group is quite distorted in anhydrite. The four anhydrite samples have structural trends where the a, b, and c unit-cell parameters increase linearly with increasing unit-cell volume, V, and their average <Ca-O> and <S-O> distances are nearly constant. The grand mean <Ca-O> = 2.4660(2) Å, and grand mean <S-O> = 1.4848(3) Å, the latter is longer than 1.480(1) Å in celestite, SrSO4, as expected.

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