Structural changes in nanocrystalline mackinawite (FeS) at high pressure

2008 ◽  
Vol 42 (1) ◽  
pp. 15-21 ◽  
Author(s):  
L. Ehm ◽  
F. M. Michel ◽  
S. M. Antao ◽  
C. D. Martin ◽  
P. L. Lee ◽  
...  
Keyword(s):  
High Pressure ◽  
Pair Distribution Function ◽  
Structural Changes ◽  
Function Analysis ◽  
Structural Phase ◽  
High Energy ◽  
Particle Sizes ◽  
Grain Size Effect ◽  
X Ray ◽  
First Order

The high-pressure behavior of nanocrystalline mackinawite (FeS) with particle sizes of 6, 7 and 8 nm has been investigated by high-energy X-ray total scattering and pair distribution function analysis. An irreversible first-order structural phase transition from tetragonal mackinawite to orthorhombic FeS-II was observed at about 3 GPa. The transition is induced by the closure of the van der Waals gap in the layered mackinawite structure. A grain size effect on the transition pressure and the compressibility was observed.

scholarly journals Time-resolved pair distribution function analysis of disordered materials on beamlines BL04B2 and BL08W at SPring-8

2018 ◽  
Vol 25 (6) ◽  
pp. 1627-1633 ◽  
Author(s):  
Koji Ohara ◽  
Satoshi Tominaka ◽  
Hiroki Yamada ◽  
Masakuni Takahashi ◽  
Hiroshi Yamaguchi ◽  
...  
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Structural Changes ◽  
Function Analysis ◽  
Image Data ◽  
High Energy ◽  
Disordered Materials ◽  
X Rays ◽  
Two Dimensional ◽  
Time Resolved

A dedicated apparatus has been developed for studying structural changes in amorphous and disordered crystalline materials substantially in real time. The apparatus, which can be set up on beamlines BL04B2 and BL08W at SPring-8, mainly consists of a large two-dimensional flat-panel detector and high-energy X-rays, enabling total scattering measurements to be carried out for time-resolved pair distribution function (PDF) analysis in the temperature range from room temperature to 873 K at pressures of up to 20 bar. For successful time-resolved analysis, a newly developed program was used that can monitor and process two-dimensional image data simultaneously with the data collection. The use of time-resolved hardware and software is of great importance for obtaining a detailed understanding of the structural changes in disordered materials, as exemplified by the results of commissioned measurements carried out on both beamlines. Benchmark results obtained using amorphous silica and demonstration results for the observation of sulfide glass crystallization upon annealing are introduced.

scholarly journals Total-scattering pair-distribution function analysis of zinc from high-energy synchrotron data

2019 ◽  
Vol 33 (33) ◽  
pp. 1950410 ◽  
Author(s):  
Ahmad S. Masadeh ◽  
Moneeb T. M. Shatnawi ◽  
Ghosoun Adawi ◽  
Yang Ren
Keyword(s):  
Crystal Structure ◽  
Distribution Function ◽  
Pair Distribution Function ◽  
Function Analysis ◽  
High Energy ◽  
Ambient Conditions ◽  
Total Scattering ◽  
X Ray ◽  
Zinc Metal ◽  
Pdf Analysis

The crystal structure of zinc metal deviates from the ideal hexagonal close packing structure by a significantly increased axial ratio (c/a). The local atomic structure of zinc metal is investigated using the total scattering atomic pair distribution function (PDF) analysis based on X-ray powder diffraction data collected at ambient conditions. The X-ray total scattering PDF analysis confirms that the crystal structure of zinc can be described in terms of wurtzite structure, but with an anomalously atomic displacement parameters [Formula: see text], indicating a significant displacement disorder along the [Formula: see text]-axis. For the long [Formula: see text]-range PDF refinements, the thermal motion of zinc shows a notable anisotropy as expressed by the ratio [Formula: see text]/[Formula: see text] of 2.5 at ambient conditions. This average distortion level along the [Formula: see text]-axis, was not reflected locally for the features below 5.0 Å as it fits the high [Formula: see text] region. Based on PDF refinements over different [Formula: see text]-ranges, we measure an interesting increase of the [Formula: see text] value with decreasing the [Formula: see text]-range of the refinement. This suggests that the local structure features in zinc metal differ from the average structure ones.

Structural stability of WS2 under high pressure

2014 ◽  
Vol 28 (25) ◽  
pp. 1450168 ◽  
Author(s):  
Nirup Bandaru ◽  
Ravhi S. Kumar ◽  
Jason Baker ◽  
Oliver Tschauner ◽  
Thomas Hartmann ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Structural Changes ◽  
High Pressures ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diamond Anvil ◽  
Heating Up

Structural behavior of bulk WS 2 under high pressure was investigated using synchrotron X-ray diffraction and diamond anvil cell up to 52 GPa along with high temperature X-ray diffraction and high pressure Raman spectroscopy analysis. The high pressure results obtained from X-ray diffraction and Raman analysis did not show any pressure induced structural phase transformations up to 52 GPa. The high temperature results show that the WS 2 crystal structure is stable upon heating up to 600°C. Furthermore, the powder X-ray diffraction obtained on shock subjected WS 2 to high pressures up to 10 GPa also did not reveal any structural changes. Our results suggest that even though WS 2 is less compressible than the isostructural MoS 2, its crystal structure is stable under static and dynamic compressions up to the experimental limit.

scholarly journals In situ X-ray pair distribution function analysis of accelerated carbonation of a synthetic calcium–silicate–hydrate gel

2015 ◽  
Vol 3 (16) ◽  
pp. 8597-8605 ◽  
Author(s):  
Antoine E. Morandeau ◽  
Claire E. White
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Calcium Silicate Hydrate ◽  
Function Analysis ◽  
High Energy ◽  
Accelerated Carbonation ◽  
X Ray ◽  
Kinetics Of Reaction ◽  
Kinetics Of

The kinetics of reaction and the local atomic structure of carbonating C–S–H gel are characterised using high-energy synchrotron radiation.

scholarly journals High-pressure pair distribution function (PDF) measurement using high-energy focused x-ray beam

2016 ◽  
Author(s):  
Xinguo Hong ◽  
Lars Ehm ◽  
Zhong Zhong ◽  
Sanjit Ghose ◽  
Thomas S. Duffy ◽  
...  
Keyword(s):  
High Pressure ◽  
Distribution Function ◽  
Pair Distribution Function ◽  
High Energy ◽  
X Ray

scholarly journals High-energy X-ray focusing and high-pressure pair distribution function measurement

2016 ◽  
Author(s):  
Xinguo Hong ◽  
Lars Ehm ◽  
Zhong Zhong ◽  
Sanjit Ghose ◽  
Thomas S. Duffy ◽  
...  
Keyword(s):  
High Pressure ◽  
Distribution Function ◽  
Pair Distribution Function ◽  
High Energy ◽  
Function Measurement ◽  
X Ray

scholarly journals Pair distribution function analysis at the Brazilian synchrotron light source

2014 ◽  
Vol 70 (a1) ◽  
pp. C872-C872 ◽  
Author(s):  
Martín Saleta ◽  
Valmor Mastelaro ◽  
Eduardo Granado
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Room Temperature ◽  
Function Analysis ◽  
National Laboratory ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Synchrotron Light

The XDS beamline of the Synchrotron Light National Laboratory (LNLS), was designed to take advantage of the 4T superconducting multipole wiggler inserted in the storage ring. This multipurpose beam line is employed for X-ray diffraction and X-ray absorption spectroscopy in the energy range between 5 and 30 keV. The X-ray diffraction patterns can be acquired in two different arrangements: a) Bragg-Brentano configuration, using a scintillation detector with an analyzer and b) Debye-Scherrer configuration, where the sample is mounted into capillaries and the diffraction pattern is acquired with an arrangement of 6 Mythen detectors or a scintillator. The sample can be measured at different atmospheres and temperatures. The viability of the beamline for pair distribution function analysis (PDF) was tested measuring two different standards: 1) Al2O3 and 2) BaTiO3. The patterns were acquired at room temperature using the two detection setups at an energy of 20 keV. The samples were mounted inside 0.3 mm boron-rich glass capillaries. In addition to the sample pattern, we also measured the empty capillary (background) to subtract it to the sample data. The acquired and normalized patterns were converted into total scattering PDF (G(r)) with the PDFgetX3.[1] The experimental G(r) was fitted with the PDFgui.[2] Both data sets were fitted in the corresponding structural phase with cell parameters close to the ones reported in the literature. In the special case of the BaTiO3 sample, it was very carefully modeled. We particularly focused in evaluating if we can discriminate the correct structural phase, as this sample presents different phases (orthorhombic, tetragonal and cubic). We could identify that the sample, at room temperature, was at the expected tetragonal phase. Finally, we will present a preliminary analysis of the following systems: Pb1-xRxZr1-yTiyO3 (R=La&Ba) and Ba1-xRxZr1-yTiyO3 (R=La&Ca) at the ferro- and paraelectric states by PDF.

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