scholarly journals Visualizing mineralization processes and fossil anatomy using synchronous synchrotron X-ray fluorescence and X-ray diffraction mapping

2020 ◽  
Vol 17 (169) ◽  
pp. 20200216 ◽  
Author(s):  
Pierre Gueriau ◽  
Solenn Réguer ◽  
Nicolas Leclercq ◽  
Camila Cupello ◽  
Paulo M. Brito ◽  
...  
Keyword(s):  
Cross Sections ◽  
Soft Tissues ◽  
Local Strain ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray ◽  
Area Detector ◽  
Transmission Geometry ◽  
Mineralization Processes ◽  
Elemental Data

Fossils, including those that occasionally preserve decay-prone soft tissues, are mostly made of minerals. Accessing their chemical composition provides unique insight into their past biology and/or the mechanisms by which they preserve, leading to a series of developments in chemical and elemental imaging. However, the mineral composition of fossils, particularly where soft tissues are preserved, is often only inferred indirectly from elemental data, while X-ray diffraction that specifically provides phase identification received little attention. Here, we show the use of synchrotron radiation to generate not only X-ray fluorescence elemental maps of a fossil, but also mineralogical maps in transmission geometry using a two-dimensional area detector placed behind the fossil. This innovative approach was applied to millimetre-thick cross-sections prepared through three-dimensionally preserved fossils, as well as to compressed fossils. It identifies and maps mineral phases and their distribution at the microscale over centimetre-sized areas, benefitting from the elemental information collected synchronously, and further informs on texture (preferential orientation), crystallite size and local strain. Probing such crystallographic information is instrumental in defining mineralization sequences, reconstructing the fossilization environment and constraining preservation biases. Similarly, this approach could potentially provide new knowledge on other (bio)mineralization processes in environmental sciences. We also illustrate that mineralogical contrasts between fossil tissues and/or the encasing sedimentary matrix can be used to visualize hidden anatomies in fossils.

scholarly journals Visualizing mineralization processes and fossil anatomy using synchronous synchrotron X-ray fluorescence and X-ray diffraction mapping

2020 ◽  
Author(s):  
Pierre Gueriau ◽  
Solenn Réguer ◽  
Nicolas Leclercq ◽  
Camila Cupello ◽  
Paulo M. Brito ◽  
...  
Keyword(s):  
Cross Sections ◽  
Soft Tissues ◽  
Imaging Techniques ◽  
Local Strain ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray ◽  
Area Detector ◽  
Exceptional Preservation ◽  
Mineralization Processes

Paleontologists have always tested, used and developed cutting edge imaging techniques to produce the most complete and accurate descriptions of their fossils. Nowadays, efforts are largely driven by taphonomic studies, especially those investigating the exceptional preservation of organic molecules or soft tissues, leading to a series of developments towards molecular and elemental imaging. Paradoxically, although fossils are mostly mineralized materials only the latter is commonly used to infer their mineral composition, but X-ray diffraction, which specifically provides phase identification, received little attention. Here, we show the use of synchrotron radiation to generate, synchronously to X-ray fluorescence major-to-trace elemental maps, megapixel mineralogical maps in transmission geometry using a two-dimensional area detector placed behind the fossil. This approach was applied to millimeter-thick cross-sections prepared through three-dimensionally preserved fossils, as well as to flat fossils. It allows for mineral phases identification (benefitting from the elemental information collected synchronously) and localization at the microscale over centimetric lateral size objects, and further gives information on texture (preferential orientation), crystallites size and local strain, showing great potential for taphonomic studies, as well as other poorly understood (bio)mineralization processes in environmental sciences. We also illustrate that mineralogical contrasts between fossil tissues and/or the encasing sedimentary matrix can be used to visualize hidden anatomies in fossils.

Pair distribution function analysis of X-ray diffraction from amorphous spheres in an asymmetric transmission geometry: application to a Zr58.5Cu15.6Ni12.8Al10.3Nb2.8glass

2013 ◽  
Vol 46 (4) ◽  
pp. 999-1007 ◽  
Author(s):  
J. C. Bendert ◽  
N. A. Mauro ◽  
K. F. Kelton
Keyword(s):  
Distribution Function ◽  
Error Propagation ◽  
Pair Distribution Function ◽  
Function Analysis ◽  
X Ray Diffraction ◽  
Asymmetric Transmission ◽  
X Ray ◽  
Area Detector ◽  
Spherical Sample ◽  
Transmission Geometry

A method for the calculation of the pair distribution and structure functions from X-ray intensity data obtained with an area detector for an off-center incident X-ray beam on an amorphous sphere is presented. Error propagation for converting from the structure function to the pair distribution function is also described, including a summation series approach to treat the error from a high-qtruncation. A Zr58.5Cu15.6Ni12.8Al10.3Nb2.8glass (Vitreloy 106a) is used to demonstrate the techniques. In particular, the semi-analytical corrections presented to calculate the effects of secondary scatter within and asymmetric transmission through a spherical sample are verified.

scholarly journals Local Strain Distribution in ZnO Microstructures Visualized with Scanning Nano X‐Ray Diffraction and Impact on Electrical Properties

2021 ◽  
pp. 2100201
Author(s):  
Philipp Jordt ◽  
Stjepan B. Hrkac ◽  
Jorit Gröttrup ◽  
Anton Davydok ◽  
Christina Krywka ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Strain Distribution ◽  
Local Strain ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals An Insight into Chemistry and Structure of Colloidal 2D-WS2 Nanoflakes: Combined XPS and XRD Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1969
Author(s):  
Riccardo Scarfiello ◽  
Elisabetta Mazzotta ◽  
Davide Altamura ◽  
Concetta Nobile ◽  
Rosanna Mastria ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Xrd Analysis ◽  
Crystal Habit ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Evaluation ◽  
Rational Understanding ◽  
Structural Inspection

The surface and structural characterization techniques of three atom-thick bi-dimensional 2D-WS2 colloidal nanocrystals cross the limit of bulk investigation, offering the possibility of simultaneous phase identification, structural-to-morphological evaluation, and surface chemical description. In the present study, we report a rational understanding based on X-ray photoelectron spectroscopy (XPS) and structural inspection of two kinds of dimensionally controllable 2D-WS2 colloidal nanoflakes (NFLs) generated with a surfactant assisted non-hydrolytic route. The qualitative and quantitative determination of 1T’ and 2H phases based on W 4f XPS signal components, together with the presence of two kinds of sulfur ions, S22− and S2−, based on S 2p signal and related to the formation of WS2 and WOxSy in a mixed oxygen-sulfur environment, are carefully reported and discussed for both nanocrystals breeds. The XPS results are used as an input for detailed X-ray Diffraction (XRD) analysis allowing for a clear discrimination of NFLs crystal habit, and an estimation of the exact number of atomic monolayers composing the 2D-WS2 nanocrystalline samples.

Polyhedral characteristics of the cosalite-type crystal structures

2019 ◽  
Vol 57 (5) ◽  
pp. 647-662
Author(s):  
Sabina Kovač ◽  
Predrag Dabić ◽  
Aleksandar Kremenović ◽  
Aleksandar Pačevski ◽  
Ljiiljana Karanović ◽  
...  
Keyword(s):  
Crystal Data ◽  
Chemical Formula ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Area Detector ◽  
Octahedral Sites ◽  
Distorted Octahedral ◽  
Cation Substitutions ◽  
Type Crystal

Abstract The crystal structure of cosalite from the Trepča orefield was refined in the orthorhombic space group Pnma [a = 23.7878 (9), b = 4.0566 (3), c = 19.1026 (8) Å, V = 1843.35 (17) Å3, Z = 2] from single-crystal data (MoKα X-ray diffraction, CCD area detector) to the conventional R1 factor 0.031 for 1516 unique reflections with I > 2σ(I). The chemical formula (Cu0.15Ag0.24)+(Fe0.19Pb7.20)2+(Bi7.06Sb1.06)3+S20, calculated on the basis of 20 S atoms per formula unit, was determined by WDX. The unit cell contains 18 + 2 symmetrically nonequivalent atomic sites: 10 occupied by S; two by pure Pb (Pb3 and Pb4); one by pure Bi (Bi1); two by a combination of Bi and small amounts of Sb (Bi2/Sb2, Bi4/Sb3); two by Pb and Bi, and in one of these also by a small amount of Ag [Me1 = Pb2 >> Bi5 > Ag1, Me3 = Pb1 >> Bi3]; and finally one site, Me2 (Bi6 >> □), is partly occupied by Bi and partly split into an additional two adjacent trigonal planar “interstitial positions”, Cu1 and Cu2, where small amounts of Cu, Ag, and Fe can be situated. All atoms are at 4c special positions at y = 0.25 or 0.75. The structure consists of slightly to moderately distorted MeS6 octahedra sharing edges, bicapped trigonal PbS8 coordination prisms, and fairly distorted Cu1S6 and Cu2S4 polyhedra. The effects of the cation substitutions, bond valence sums, and the polyhedral characteristics are compared with other published cosalite-type structures. Among known cosalite-type structures, the largest volume contraction is shown by sample 4 (Altenberg) and involves the replacement of large cations (Bi3+ and Pb2+) by the smaller Sb3+, as well as Cu+ and Ag+. These replacements are reflected in the variations of individual Me–S bond distances, which are accompanied by variations in average Me–S distances. The degree of polyhedral distortion, Δ, progressively increases for the four Bi-hosting sites of nine cosalite-type structures: Me2 < Bi2 < Bi1 < Bi4. The Bi4 and Me3 are the most and the Me1 and Me2 are the least distorted octahedral sites of the nine cosalite-type structures.

Diffraction

2012 ◽  
Vol 20 (2) ◽  
pp. 7-7
Author(s):  
Charles Lyman
Keyword(s):  
Electron Diffraction ◽  
100Th Anniversary ◽  
Primary Phase ◽  
Phase Identification ◽  
X Rays ◽  
X Ray Diffraction ◽  
Identification Methods ◽  
X Ray ◽  
Structure Of Matter

This year marks the 100th anniversary of the discovery of X-ray diffraction and the 85th anniversary of electron diffraction (see Microscopy Pioneers). For most of the time since their introduction, microscopists have known these two techniques as the primary phase identification methods used in conjunction with various microscopies. However, these two diffraction methods also have played enormous roles in understanding the structure of matter, as well as the nature of both X rays and electrons.

Computer Techniques for Faster X-Ray Diffraction Phase Identification

1984 ◽  
pp. 21-26 ◽  
Author(s):  
Raymond P. Goehner ◽  
Mary F. Garbauskas
Keyword(s):  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Electroless Deposition of Cu-SWCNT Composites

2019 ◽  
Vol 5 (4) ◽  
pp. 61 ◽  
Author(s):  
Raja ◽  
Esquenazi ◽  
Jones ◽  
Li ◽  
Brinson ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electroless Deposition ◽  
Reaction Times ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
Copper Surfaces ◽  
X Ray ◽  
Dispersing Agent ◽  
Defect Sites ◽  
Walled Carbon Nanotubes

In this work, as-received HiPCO single walled carbon nanotubes (SWCNTs) are incorporated in a controllable manner at various concentrations into Cu-SWCNT composites via electroless plating, by varying the related reaction times, with polyethylene glycol (PEG) used as a dispersing agent. The resultant samples were analyzed using scanning electron microscopy (SEM) for morphology assessment, energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS) for elemental analysis, X-ray diffraction (XRD) for the assessment of crystal phase identification, and Raman spectroscopy for the confirmation of the presence of the incorporated SWCNTs. The Cu-SWCNT composites were found to contain carbon, catalytic iron (associated with the raw, as-received SWCNTs), oxygen, and copper; the latter was found to be inversely proportional to carbon and iron contents. The oxygen (associated with both the SWCNT defect sites and oxidized copper surfaces) remained more or less constant regardless of the proportion of SWCNTs in the composites. The Raman IG:ID ratio remains within the experimental error constant, indicating that the electroless deposition does not have a deleterious effect on the SWCNTs. At short deposition times, SEM revealed a relatively dense structure comprising a distinctive fibrous morphology, suggestive of an underlying SWCNT substrate coated with copper; however, with increasing deposition, a more porous morphology is observed. The size of the granular particles increases up until 10 min of reaction, after which time it remains unchanged.

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