scholarly journals Preferred orientation of ettringite in concrete fractures

2009 ◽  
Vol 42 (3) ◽  
pp. 429-432 ◽  
Author(s):  
Hans-Rudolf Wenk ◽  
Paulo J. M. Monteiro ◽  
Martin Kunz ◽  
Kai Chen ◽  
Nobumichi Tamura ◽  
...  
Keyword(s):  
Single Crystal ◽  
Elastic Properties ◽  
Elastic Anisotropy ◽  
Rietveld Method ◽  
Orientation Distribution ◽  
Sulfate Attack ◽  
X Ray ◽  
Fracture Surfaces ◽  
Concrete Fractures ◽  
Loss Of Strength

Sulfate attack and the accompanying crystallization of fibrous ettringite [Ca6Al2(OH)12(SO4)3·26H2O] cause cracking and loss of strength in concrete structures. Hard synchrotron X-ray microdiffraction is used to quantify the orientation distribution of ettringite crystals. Diffraction images are analyzed using the Rietveld method to obtain information on textures. The analysis reveals that thecaxes of the trigonal crystallites are preferentially oriented perpendicular to the fracture surfaces. By averaging single-crystal elastic properties over the orientation distribution, it is possible to estimate the elastic anisotropy of ettringite aggregates.

Elastic anisotropy of oceanic serpentinites – influence of CPO and microstructure

2021 ◽  
Author(s):  
Rebecca Kühn ◽  
Jan Behrmann ◽  
Rüdiger Kilian ◽  
Bernd Leiss ◽  
Michael Stipp
Keyword(s):  
Physical Properties ◽  
Elastic Properties ◽  
Seismic Data ◽  
Elastic Anisotropy ◽  
Rietveld Method ◽  
High Energy ◽  
Low Grade ◽  
Crystallographic Preferred Orientation ◽  
X Ray ◽  
The Impact

<p>Physical properties of rocks are mainly controlled by the modal composition, crystallographic preferred orientation (CPO) and microstructure of a rock. One of the most relevant physical properties related to the interpretation of seismic data are the elastic properties of a mineral aggregate. Changes of elastic properties - and hence changes in our interpretation of the tectonic architecture of certain regions - can be related to mineral reactions and deformation.</p><p>In order to explore the impact of mineral reaction and deformation on elastic anisotropy, we study oceanic serpentinites formed at low-grade metamorphic conditions by hydration of peridotites. Samples are obtained from the Atlantis Massif, which is an Oceanic Core Complex located at 30°N, Mid-Atlantic Ridge. During IODP Expedition 357, oceanic serpentinites were recovered from drill cores along the southern wall of the Massif. Fully serpentinized samples displaying variable microstructures were analyzed regarding the influence of microstructure and CPO on the overall elastic anisotropy. Microstructure analysis was based on optical microscopy and large area micro X-ray fluorescence mapping. For CPO analysis synchrotron high energy X-ray diffraction in combination with the Rietveld method was applied and the derived CPO was used to compute seismic properties.</p><p>Serpentinites with a typical mesh microstructure are interpreted to represent undeformed samples and show a close to uniform CPO. The increase in fabric anisotropy of vein-like magnetite aggregates is interpreted as an increase in deformation. Samples show a single c-axis-maximum and enhanced CPO. Calculated seismic anisotropies show up to >5% anisotropy for compressional waves (Vp) and shear wave splitting up to 0.15 km/s in the deformed samples. Hence, such an anisotropy can be used to differentiate deformed from undeformed zones in seismic data sets using the elastic anisotropy data.</p>

Structure Refinements of the Layered Intergrowth Phases SbIIISbV x A 1−x TiO6 (x≃0, A = Ta, Nb) Using Synchrotron X-ray Powder Diffraction Data

1997 ◽  
Vol 53 (6) ◽  
pp. 861-869 ◽  
Author(s):  
C. D. Ling ◽  
J. G. Thompson ◽  
S. Schmid ◽  
D. J. Cookson ◽  
R. L. Withers
Keyword(s):  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Homologous Series ◽  
Rietveld Method ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Synchrotron Source ◽  
X Ray ◽  
The Family

The structures of the layered intergrowth phases SbIIISb^{\rm V}_xAl-xTiO6 (x \simeq 0, A = Ta, Nb) have been refined by the Rietveld method, using X-ray diffraction data obtained using a synchrotron source. The starting models for these structures were derived from those of Sb^{\rm III}_3Sb^{\rm V}_xA 3−xTiO14 (x = 1.26, A = Ta and x = 0.89, A = Nb), previously solved by single-crystal X-ray diffraction. There were no significant differences between the derived models and the final structures, validating the approach used to obtain the models and confirming that the n = 1 and n = 3 members of the family, Sb^{\rm III}_nSb^{\rm V}_xA n−xTiO4n+2 are part of a structurally homologous series.

Anisotropy of experimentally compressed kaolinite-illite-quartz mixtures

Geophysics ◽  
2009 ◽  
Vol 74 (1) ◽  
pp. D13-D23 ◽  
Author(s):  
Marco Voltolini ◽  
Hans-Rudolf Wenk ◽  
Nazmul Haque Mondol ◽  
Knut Bjørlykke ◽  
Jens Jahren
Keyword(s):  
Single Crystal ◽  
Elastic Properties ◽  
Compaction Pressure ◽  
Clay Content ◽  
Orientation Distribution ◽  
Rietveld Analysis ◽  
Preferred Orientation ◽  
P Wave ◽  
Velocity Anisotropy ◽  
Pole Figures

The anisotropy of physical properties is a well-known characteristic of many clay-bearing rocks. This anisotropy has important implications for elastic properties of rocks and must be considered in seismic modeling. Preferred orientation of clay minerals is an important factor causing anisotropy in clay-bearing rocks such as shales and mudstones that are the main cap rocks of oil reservoirs. The preferred orientation of clays depends mostly on the amount of clays and the degree of compaction. To study the effect of these parameters, we prepared several samples compressing (at two effective vertical stresses) a mixture of clays (illite and kaolinite) and quartz (silt) with different clay/quartz ratios. The preferred orientation of the phases was quantified with Rietveld analysis on synchrotron hard X-ray images. Pole figures for kaolinite and illite display a preferred orientationof clay platelets perpendicular to the compaction direction, increasing in strength with clay content and compaction pressure. Quartz particles have a random orientation distribution. Aggregate elastic properties can be estimated by averaging the single-crystal properties over the orientation distribution obtained from the diffraction data analysis. Calculated P-wave velocity anisotropy ranges from 0% (pure quartz sample) to 44% (pure clay sample, highly compacted), but calculated velocities are much higher than measured velocities. This is attributed to uncertainties about single-crystal elastic properties and oriented micropores and limited grain contacts that are not accounted for in the model. In this work, we present an effective method to obtain quantitative data, helping to evaluate the role of clay percentage and compaction pressure on the anisotropy of elastic properties of clay-bearing rocks.

X-ray Diffraction Study of the Crystal Structure of the Tl Ternary Chalcogenides Tl2x In2(1−x)Se2, x = 0.2, 0.3,...0.9

1998 ◽  
Vol 54 (4) ◽  
pp. 358-364 ◽  
Author(s):  
K. G. Hatzisymeon ◽  
S. C. Kokkou ◽  
A. N. Anagnostopoulos ◽  
P. I. Rentzeperis
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Rietveld Method ◽  
Direct Methods ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Volume Decrease

A series of thallium ternary chalcogenides with the composition Tl2x In2(1−x)Se2, x = 0.2, 0.3,...0.9, have been studied by X-ray powder and, for some of them, single-crystal diffraction. They are tetragonal, space group I4/mcm, Z = 4, and isostructural with the binary semiconductor TlSe. Their crystal structures have been solved by direct methods and refined by the Rietveld method to a precision which is satisfactorily comparable to single-crystal results. As x is changed from x = 0.2 to x = 0.9 the unit-cell parameters and volume decrease or increase following Kurnakov's law, which is valid for solid solutions. Refined positional parameters of Se, In—Se and Tl—Se bond lengths vary with x also according to the same law. The distribution of In and Tl cations in 4(a) and 4(b) sites depends on the stoichiometry x and the crystals are composed of [In3+Se2]_{\infty}^- chains along the c axis in which InSe4 tetrahedra share edges; the chains are interconnected with Tl+(In+) ions.

Preferred orientation and elastic anisotropy of illite-rich shale

Geophysics ◽  
2007 ◽  
Vol 72 (2) ◽  
pp. E69-E75 ◽  
Author(s):  
Hans-Rudolf Wenk ◽  
Ivan Lonardelli ◽  
Hermann Franz ◽  
Kurt Nihei ◽  
Seiji Nakagawa
Keyword(s):  
Grain Size ◽  
Seismic Anisotropy ◽  
Elastic Anisotropy ◽  
Rietveld Method ◽  
Transverse Isotropy ◽  
Orientation Distribution ◽  
High Energy ◽  
Quantitative Information ◽  
Preferred Orientation ◽  
X Rays

Shales display significant seismic anisotropy that is attributed in part to preferred orientation of constituent minerals. This orientation pattern has been difficult to quantify because of the poor crystallinity and small grain size of clay minerals. A new method is introduced that uses high-energy synchrotron X-rays to obtain diffraction images in transmission geometry and applies it to an illite-rich shale. The images are analyzed with the crystallographic Rietveld method to obtain quantitative information about phase proportions, crystal structure, grain size, and preferred orientation (texture) that is the focus of the study. Textures for illite are extremely strong, with a maximum of 10 multiples of a random distribution for (001) pole figures. From the three-dimensional orientation distribution of crystallites, and single-crystal elastic properties, the intrinsic anisotropic elastic constants of the illite aggregate (excluding contribution from aligned micropores) can be calculated by appropriate medium averaging. The illitic shale displays roughly transverse isotropy with [Formula: see text] close to [Formula: see text] and more than twice as strong as [Formula: see text]. This method will lend itself to investigate complex polymineralic shales and quantify the contribution of preferred orientation to macroscopic anisotropy.

Elastic Properties of L10-Ordered Single Crystals

2007 ◽  
Vol 26-28 ◽  
pp. 221-224 ◽  
Author(s):  
C. Wang ◽  
Katsushi Tanaka ◽  
Kyosuke Kishida ◽  
Haruyuki Inui
Keyword(s):  
Single Crystal ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Elastic Properties ◽  
Elastic Constants ◽  
Elastic Anisotropy ◽  
Axial Ratio ◽  
Spectroscopy Technique ◽  
Complete Set

The temperature dependence of single-crystal elastic constants of L10-ordered single-crystals of FePd . A complete set of elastic constants has been determined with the resonance ultrasound spectroscopy technique. The compounds clearly show a tetragonal elastic anisotropy, c11 < c33 and c44 < c66. The temperature dependencies of the anisotropies are not simply explained by the variation of axial ratio (c/a) of the crystal.

scholarly journals New intermetallic La117Ru57Sn112.

2014 ◽  
Vol 70 (a1) ◽  
pp. C507-C507
Author(s):  
Vera Gribanova ◽  
Alexander Gribanov ◽  
Elena Murashova ◽  
Konstantin Kalmykov
Keyword(s):  
Single Crystal ◽  
Rietveld Method ◽  
Direct Methods ◽  
Ternary Systems ◽  
Lattice Parameter ◽  
X Ray ◽  
Good Convergence ◽  
Convergence Results ◽  
Crystal Model ◽  
Equiatomic Alloy

The new ternary compound with giant unit cell La117Ru57Sn112 has been yielded by interaction between pure components lanthanum, ruthenium and tin and investigated by X-ray diffraction and scanning electron microscopy (SEM) in combination with energy dispersive X-ray spectroscopy (EDX) means. Previously, intermetallics with cobalt of similar composition and structure were found in the ternary systems and Dy-Co-Sn and Pr-Co-Sn – Dy117Co57Sn112 and Pr117Co57Sn112 respectively [1, 2]. The intermetallic La117Ru57Sn112 crystallizes in a cubic Dy117Co57Sn112 type structure with space group Fm-3m (No. 225) and lattice parameter a = 31.529(5). A single-crystal suitable for the X-ray measurements was isolated from the of the equiatomic alloy La33.3Ru33.3Sn33.4. The structure was solved by means of direct methods and refined using the SHELXS-97 and SHELXL-97 programs (R1 = 0.033 for 1042 Fo > 4σ(Fo) and 0.061 for all collected data). The additional sample of the La40.2Ru19.9Sn39.9 composition was prepared and investigated X-ray by powder diffraction technique (CuKα1 radiation, 5 < 2Θ < 900). The collected intensities data were refined by the Rietveld method using the La117Ru57Sn112 single crystal model and FullProf program. Based on a minimum of differences between the observed and calculated theoretically intensities one can judge the good convergence results.

scholarly journals Single Crystal Elastic Properties of Hemimorphite, a Novel Hydrous Silicate

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 425
Author(s):  
Yingzhe Li ◽  
Jay D. Bass
Keyword(s):  
Single Crystal ◽  
Elastic Properties ◽  
Wave Velocity ◽  
Elastic Moduli ◽  
Elastic Anisotropy ◽  
Pure Shear ◽  
P Wave ◽  
Upper And Lower Bounds ◽  
Molecular Water ◽  
High Degree

Hemimorphite, with the chemical formula Zn4Si2O7(OH)2·H2O, contains two different types of structurally bound hydrogen: molecular water and hydroxyl. The elastic properties of single-crystal hemimorphite have been determined by Brillouin spectroscopy at ambient conditions, yielding tight constraints on all nine single-crystal elastic moduli (Cij). The Voigt–Reuss–Hill (VRH) averaged isotropic aggregate elastic moduli are KS (VRH) = 74(3) GPa and μ (VRH) = 27(2) GPa, for the adiabatic bulk modulus and shear modulus, respectively. The average of the Hashin–Shtrickman (HS) bounds are Ks (HS) = 74.2(7) GPa and and μ (HS) = 26.5(6) GPa. Hemimorphite displays a high degree of velocity anisotropy. As a result, differences between upper and lower bounds on aggregate properties are large and the main source of uncertainty in Ks and μ. The HS average P wave velocity is VP = 5.61(4) km/s, and the HS S-wave velocity is VS = 2.77(3) km/s. The high degree of elastic anisotropy among the on-diagonal longitudinal and pure shear moduli of hemimorphite are largely explained by its distinctive crystal structure.

Structure Re-determination of LASSBio-294 – a cardioactive compound of the N-acylhydrazone class – using X-ray powder diffraction data

2013 ◽  
Vol 28 (S2) ◽  
pp. S491-S509 ◽  
Author(s):  
Fanny N. Costa ◽  
Fabio Furlan Ferreira ◽  
Tiago F. da Silva ◽  
Eliezer J. Barreiro ◽  
Lídia M. Lima ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Goodness Of Fit ◽  
Rietveld Method ◽  
Therapeutic Interventions ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Cell Parameters

Many N-acylhydrazone derivatives synthetized in LASSBio® cannot be prepared as single crystals of sufficient size and/or quality for structure determination to be carried out using single crystal X-ray diffraction techniques. This article highlights the opportunity for determining crystal structures of this class of compounds directly from powder diffraction data. For this task, the crystal structure of LASSBio-294 was re-determined by means of conventional X-ray powder diffraction data and so, compared with the crystal structure already determined for single crystal data. LASSBio-294 is a cardioactive compound of the N-acylhydrazone class, which can become part of the therapeutic interventions designed to decrease exertional fatigue, and, consequently, improve the quality of life of patients suffering from chronic heart failure. Its final crystal structure was refined by means of the Rietveld method (Rietveld, 1967; 1969). This drug crystallizes in a monoclinic (P21/c) space group, with unit cell parameters a = 11.3413(3) Å, b = 12.3573(4) Å, c = 9.0158(3) Å, β = 89.821(2)°, V = 1263.55(7) Å3, Z = 4, Ź = 1 and ρcalc = 1.4419(1) g cm−3. The goodness-of-fit indicator and R-factors were, respectively: χ2 = 1.203, RBragg = 0.696%, Rwp = 5.59%, Rexp = 4.65% and Rp = 4.18%. The molecules in LASSBio-294 are H-bonded along the c-axis involving the atoms N(3)–H(8)···O(4).

Rietveld refinement of chapmanite SbFe2Si2O8OH, a TO dioctahedral kaolinite-like mineral

1998 ◽  
Vol 13 (1) ◽  
pp. 44-49 ◽  
Author(s):  
P. Ballirano ◽  
A. Maras ◽  
F. Marchetti ◽  
S. Merlino ◽  
N. Perchiazzi
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Rietveld Refinement ◽  
High Voltage ◽  
Rietveld Method ◽  
Octahedral Sheet ◽  
Tetrahedral Sheet ◽  
X Ray ◽  
Voltage Electron ◽  
Single Crystal Study

Chapmanite, Sb(OH)Fe2(SiO4)2 is a rare mineral that generally occurs as yellow coatings on rocks from antimony mines. The very small dimensions of the crystals prevented X-ray, single-crystal study of the mineral whose structure was derived through high voltage electron diffraction (Zhukhlistov and Zvyagin, 1977). The present study confirm the correctness of the structure determined by those authors and also shows the effectiveness of the Rietveld method in the case of highly diluted phases. The structure of chapmanite is similar to that of kaolinite with two major differences: (a) the dioctahedral sheet of chapmanite contains Fe3+ instead of Al3+; (b) chapmanite has cations grasped to the octahedral sheet, on the opposite side with respect to the tetrahedral sheet.

Sign in / Sign up

Export Citation Format

Share Document