SYNCHROTRON BASED MICRO-MAPPING AND XAFS INVESTIGATION OF Fe-Mn AND EPIGENETIC INTERGROWTH WITHIN THE CAMBRIAN SHALLOW MANGANESE DEPOSITS, SOUTH JORDAN

The current work investigates the Cambrian Manganese ore deposits from Wadi Dana at central Wadi Araba region. This investigation aims to unravel the chemistry and micro-textures of the mineral paragenetic sequence for these manganese ore deposits. Particularly the Fe–Mn intimate intergrowth micro texture and the epigenetic Mn mineralization associated with Cu minerals. The combination of the synchrotron-based X-ray fluorescence (syn-XRF) micro-mapping and X-ray absorption fine structure (XAFS) techniques were used. They provide a clear picture of the elemental distribution of Mn, Fe, Cu, and Pb and other elements presented within the ore micro textures. Besides, it determines the exact elemental speciation. The results obtained gave a better understanding of the elemental atomic structures and eventually the depositional environment. Particularly, the syn-XRF micro-mapping reveals the existing of many successive evolution stages in the Mn ores. Besides, the X-ray Absorption Near Edge Structure (XANES) results showed that the micro-rhythmic texture is changing from Mn+4 (Pyrolusite) into Fe+3 (Hematite). This is evidence for the role of Eh as the main controlling factor during the ore formation. Eventually, indicating tentatively the paleoceanography setting of the Mn deposits. This is related to the continuous transgression-regression on the sea level in a semi-closed sea.

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The Role of Hydrothermal Activity in the Formation of Karst-Hosted Manganese Deposits of the Postmasburg Mn Field, Northern Cape Province, South Africa

Minerals ◽

10.3390/min9070408 ◽

2019 ◽

Vol 9 (7) ◽

pp. 408

Author(s):

Brenton J. Fairey ◽

Martin J. Timmerman ◽

Masafumi Sudo ◽

Harilaos Tsikos

Keyword(s):

Hydrothermal Fluid ◽

Hydrothermal Activity ◽

Ore Deposits ◽

Manganese Ore ◽

High Grade ◽

Ore Formation ◽

Manganese Ores ◽

Manganese Deposits ◽

Northern Cape

The Postmasburg Manganese Field (PMF), Northern Cape Province, South Africa, once represented one of the largest sources of manganese ore worldwide. Two belts of manganese ore deposits have been distinguished in the PMF, namely the Western Belt of ferruginous manganese ores and the Eastern Belt of siliceous manganese ores. Prevailing models of ore formation in these two belts invoke karstification of manganese-rich dolomites and residual accumulation of manganese wad which later underwent diagenetic and low-grade metamorphic processes. For the most part, the role of hydrothermal processes and metasomatic alteration towards ore formation has not been adequately discussed. Here we report an abundance of common and some rare Al-, Na-, K- and Ba-bearing minerals, particularly aegirine, albite, microcline, banalsite, sérandite-pectolite, paragonite and natrolite in Mn ores of the PMF, indicative of hydrothermal influence. Enrichments in Na, K and/or Ba in the ores are generally on a percentage level for most samples analysed through bulk-rock techniques. The presence of As-rich tokyoite also suggests the presence of As and V in the hydrothermal fluid. The fluid was likely oxidized and alkaline in nature, akin to a mature basinal brine. Various replacement textures, particularly of Na- and K- rich minerals by Ba-bearing phases, suggest sequential deposition of gangue as well as ore-minerals from the hydrothermal fluid, with Ba phases being deposited at a later stage. The stratigraphic variability of the studied ores and their deviation from the strict classification of ferruginous and siliceous ores in the literature, suggests that a re-evaluation of genetic models is warranted. New Ar-Ar ages for K-feldspars suggest a late Neoproterozoic timing for hydrothermal activity. This corroborates previous geochronological evidence for regional hydrothermal activity that affected Mn ores at the PMF but also, possibly, the high-grade Mn ores of the Kalahari Manganese Field to the north. A revised, all-encompassing model for the development of the manganese deposits of the PMF is then proposed, whereby the source of metals is attributed to underlying carbonate rocks beyond the Reivilo Formation of the Campbellrand Subgroup. The main process by which metals are primarily accumulated is attributed to karstification of the dolomitic substrate. The overlying Asbestos Hills Subgroup banded iron formation (BIF) is suggested as a potential source of alkali metals, which also provides a mechanism for leaching of these BIFs to form high-grade residual iron ore deposits.

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Valence State of Ru at the Mn Sites in Pr0.5Sr0.5MnO3

International Journal of Modern Physics B ◽

10.1142/s0217979203021733 ◽

2003 ◽

Vol 17 (18n20) ◽

pp. 3745-3748 ◽

Cited By ~ 1

Author(s):

B. H. Kim ◽

J. S. Kim ◽

D. C. Kim ◽

Y. W. Park ◽

A. Maignan ◽

...

Keyword(s):

Valence State ◽

Carrier Density ◽

Magnetic Interactions ◽

Charge Carrier Density ◽

Edge Structure ◽

X Ray ◽

Ru Doping ◽

X Ray Absorption ◽

Tetravalent State

Valence state of the doped Ru at the Mn sites in Pr 0.5 Sr 0.5 MnO 3 has been studied using Ru K-edge X-ray absorption near-edge structure (XANES) spectroscopy. In comparison with XANES of reference ruthenates, it is found that the Mn-site doped Ru is dominantly in tetravalent state. This result suggests that the change of charge carrier density by Ru doping is not sufficient to understand drastic enhancement of ferromagnetism observed in the transport properties of Ru-doped Pr 0.5 Sr 0.5 MnO 3. The prime role of Ru in Mn 3+– O – Mn 4+ networks is discussed in terms of the valency effect and the magnetic interactions between doped Ru and Mn ions.

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Elemental distribution and Pb speciation in vegetable and cereal seeds during germination by micro X‐ray fluorescence and X‐ray absorption near‐edge structure

X-Ray Spectrometry ◽

10.1002/xrs.3034 ◽

2019 ◽

Author(s):

Liqiang Luo ◽

Yating Shen ◽

Yanhong Ma ◽

Chenfei Fu ◽

Jian Liu ◽

...

Keyword(s):

Elemental Distribution ◽

Edge Structure ◽

X Ray ◽

X Ray Absorption

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Synchrotron-Based Nano-XANES Reveals Intracellular Heterogeneity of Iron Species in Magnetotactic Bacteria

10.26434/chemrxiv.14461932.v1 ◽

2021 ◽

Author(s):

Daniel Chevrier ◽

Elisa Cerdá-Doñate ◽

Yeseul Park ◽

Fernando Cacho-Nerin ◽

Miguel Gomez-Gonzalez ◽

...

Keyword(s):

Cell Level ◽

Iron Species ◽

Intracellular Iron ◽

Iron Storage ◽

Edge Structure ◽

X Ray ◽

Magnetite Biomineralization ◽

Iron Material ◽

X Ray Absorption

<p>This report demonstrates how scanning X-ray fluorescence microscopy (SXFM) and nanoscale X-ray absorption near-edge structure (nano-XANES) can spatially and chemically identify intracellular iron species at the single-cell level, creating an opportunity to examine the role of iron storage in magnetite biomineralization. Fe K-edge nano-XANES measurements of <i>Magnetospirillum gryphiswaldense</i> in varied iron media conditions and iron storage capacity revealed intracellular iron heterogeneities through a distinction between formed magnetosomes and intracellular iron material. This work highlights the potential of nano-XANES in providing an experimental advantage in the multidisciplinary field of biomineralization.</p>

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Adsorption and oxidation of SO2 on the surface of TiO2 nanoparticles: the role of terminal hydroxyl and oxygen vacancy–Ti3+ states

Physical Chemistry Chemical Physics ◽

10.1039/d0cp00785d ◽

2020 ◽

Vol 22 (18) ◽

pp. 9943-9953

Author(s):

Bing Wang ◽

Xue Li ◽

Shanshan Liang ◽

Runxuan Chu ◽

Dan Zhang ◽

...

Keyword(s):

High Resolution ◽

Oxygen Vacancy ◽

Tio2 Nanoparticles ◽

Photoelectron Spectroscopy ◽

Flow Chamber ◽

Oxidation Reactions ◽

Edge Structure ◽

X Ray ◽

X Ray Absorption

The absorption and oxidation reactions of SO2 on TiO2 nanoparticles were investigated by using a flow chamber, synchrotron X-ray absorption near-edge structure and high resolution synchrotron X-ray photoelectron spectroscopy techniques.

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X-ray contact microscopy system for spectromicroscopy of biological specimens

Journal of Synchrotron Radiation ◽

10.1107/s0909049597018931 ◽

1998 ◽

Vol 5 (3) ◽

pp. 1099-1101 ◽

Cited By ~ 1

Author(s):

Atsushi Ito ◽

Kunio Shinohara ◽

Yutaka Mizukami ◽

Hisako Nakano ◽

Keiji Yada ◽

...

Keyword(s):

Hela Cell ◽

Absorption Edge ◽

Elemental Distribution ◽

Edge Structure ◽

X Ray ◽

X Ray Absorption ◽

Absorption Characteristics

An X-ray contact microscopy system has been developed for the study of molecular and elemental distributions in biological specimens based on X-ray absorption characteristics. The system consists of a chamber for measuring XANES (X-ray absorption near-edge structure) of biomolecules, and a contact microscopy system for dried specimens with an electronic zooming tube. With this system the elemental distribution of carbon, nitrogen, oxygen, Ca and Fe in an HeLa cell has been studied, and the DNA-related image using a peak from the XANES profile of the DNA at the K-absorption edge of phosphorus has been obtained.

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Transparent Nano-Glass-Ceramic for Photonic Applications - Distribution of RE-Doping Elements in the Fluoride Nano-Crystals Analysed by XAS and HR-TEM

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.90.111 ◽

2014 ◽

Vol 90 ◽

pp. 111-120 ◽

Cited By ~ 4

Author(s):

Araceli de Pablos-Martín ◽

Maria J. Pascual ◽

Alicia Durán

Keyword(s):

Glass Ceramics ◽

Optical Emission ◽

Elemental Distribution ◽

Edge Structure ◽

X Ray ◽

Nano Crystalline ◽

Re Elements ◽

X Ray Absorption ◽

Down Conversion ◽

O 10

Rare-earth (RE) ions-doped oxyfluoride transparent glass-ceramics containing nano-crystalline phases with very low phonon energies like LaF3, NaLaF4 and KLaF4 combine the superior optical performance of low phonon energy phases with the high mechanical, chemical and thermal stability of oxide silicates. The insertion of the doping RE ions in the fluoride nanocrystals enhances the radiative optical emission processes currently focused on up- and down-conversion emissions. Thus, a key point is to identify and quantify the RE ions in the fluoride nano-crystals. In this contribution an oxyfluoride glass and the corresponding glass-ceramics of composition 55 SiO2. 20 Al2O3.15 Na2O.10 LaF3 mol % doped with 1 mol % Tm2O3 is presented. The Tm3+ incorporation in the precipitated LaF3 nano-crystals has been analysed by two different techniques. Firstly, TEM and Energy Dispersive X-Ray Spectroscopy (EDXS) were used to perform elemental distribution mappings of RE elements that allow to directly localising RE ions in the glass and glass-ceramics. Additionally, X-ray absorption spectroscopy (XAS) measurements were performed to analyse the distribution and first coordination sphere of Tm3+ ions in the glass and glass–ceramics by using X-ray absorption near edge structure spectroscopy (XANES) and extended absorption X-ray fine structure spectroscopy (EXAFS), which have allow to quantify the Tm3+ incorporation in the LaF3 nano-crystals.

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Synchrotron-Based Nano-XANES Reveals Intracellular Heterogeneity of Iron Species in Magnetotactic Bacteria

10.26434/chemrxiv.14461932 ◽

2021 ◽

Author(s):

Daniel Chevrier ◽

Elisa Cerdá-Doñate ◽

Yeseul Park ◽

Fernando Cacho-Nerin ◽

Miguel Gomez-Gonzalez ◽

...

Keyword(s):

Cell Level ◽

Iron Species ◽

Intracellular Iron ◽

Iron Storage ◽

Edge Structure ◽

X Ray ◽

Magnetite Biomineralization ◽

Iron Material ◽

X Ray Absorption

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EFFECT OF THE ANNEALING TEMPERATURE ON THE ELECTRONIC AND ATOMIC STRUCTURES OF EXCHANGE-BIASED NiFe–FeMn BILAYERS

Surface Review and Letters ◽

10.1142/s0218625x0200221x ◽

2002 ◽

Vol 09 (01) ◽

pp. 293-298 ◽

Cited By ~ 2

Author(s):

J. M. LEE ◽

J. C. JAN ◽

J. W. CHIOU ◽

W. F. PONG ◽

M.-H. TSAI ◽

...

Keyword(s):

Annealing Temperature ◽

Nearest Neighbor ◽

White Line ◽

Edge Structure ◽

X Ray ◽

Atomic Structures ◽

Bilayer Films ◽

Fe And Mn ◽

Fourier Transform Spectra ◽

X Ray Absorption

In this study we measured the Fe, Mn, and Ni L2,3-edge X-ray absorption near-edge structure (XANES) and K-edge extended X-ray absorption fine structure (EXAFS) of the ferromagnetic (FM) NiFe and antiferromagnetic (AFM) FeMn bilayer films prepared with various annealing temperatures. The branching ratios of the white-line intensities in the Fe, Mn, and Ni L2,3-edges XANES spectra and consequently the magnetic properties of these exchange-biased FM NiFe - AFM FeMn bilayers are found to depend strongly on the annealing temperature. We find that the first peak in the Fe, Mn, and Ni K-edge EXAFS Fourier transform spectra are very similar, which suggests that the nearest-neighbor bond lengths among Fe, Mn, and Ni atoms are essentially the same in the NiFe–FeMn bilayers. However, the peaks at distances greater than ~ 3 Å appear to be sensitive to the annealing temperature especially for the Fe and Mn K-edge spectra, which suggests that annealing alters the atomic structures of the next-nearest-neighbor and more distant shells surrounding the Fe and Mn atoms in the NiFe–FeMn bilayers.

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