Combined micro X-ray absorption and fluorescence spectroscopy to map phases of complex systems: the case of sphalerite

Marini, Carlo; Rovira, Anna Maria Diaz; Ramanan, Nitya; Olszewski, W.; Joseph, Boby; Simonelli, Laura

doi:10.1038/s41598-019-55347-9

Cited by 8 publications

(4 citation statements)

References 31 publications

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“…It is well known that XANES spectra are sensitive not only to the oxidation state of absorbing atoms but also to the local atomic environment. The most straightforward approach to XANES data processing is a linear combination fitting (LCF) [14]. In the LCF method, the X-ray absorption spectrum is approximated as a linear combination of the spectra of standards.…”

Section: Xanes Spectra Analysismentioning

confidence: 99%

The State of Trace Elements (In, Cu, Ag) in Sphalerite Studied by X-Ray Absorption Spectroscopy of Synthetic Minerals

et al. 2020

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The oxidation state and local atomic environment of admixtures of In, Cu, and Ag in synthetic sphalerite crystals were determined by X-ray absorption spectroscopy (XAS). The sphalerite crystals doped with In, Cu, Ag, In–Cu, and In–Ag were synthesized utilizing gas transport, salt flux, and dry synthesis techniques. Oxidation states of dopants were determined using X-ray absorption near edge structure (XANES) technique. The local atomic structure was studied by X-ray absorption fine structure spectroscopy (EXAFS). The spectra were recorded at Zn, In, Ag, and Cu K-edges. In all studied samples, In was in the 3+ oxidation state and replaced Zn in the structure of sphalerite, which occurs with the expansion of the nearest coordination shells due to the large In ionic radius. In the presence of In, the oxidation state of Cu and Ag is 1+, and both metals can form an isomorphous solid solution where they substitute for Zn according to the coupled substitution scheme 2Zn2+ ↔ Me+ + In3+. Moreover, Ag K-edges EXAFS spectra fitting, combined with the results obtained for In- and Au-bearing sphalerite shows that the Me-S distances in the first coordination shell in the solid solution state are correlated with the ionic radii and increase in the order of Cu < Ag < Au. The distortion of the atomic structure increases in the same order. The distant (second and third) coordination shells of Cu and Ag in sphalerite are split into two subshells, and the splitting is more pronounced for Ag. Analysis of the EXAFS spectra, coupled with the results of DFT (Density Function Theory) simulations, showed that the In–In and Me+–In3+ clustering is absent when the metals are present in the sphalerite solid solution. Therefore, all studied admixtures (In, Cu, Ag), as well as Au, are randomly distributed in the matrix of sphalerite, where the concentration of the elements in the “invisible” form can reach a few tens wt.%.

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Section: Xanes Spectra Analysismentioning

confidence: 99%

The State of Trace Elements (In, Cu, Ag) in Sphalerite Studied by X-Ray Absorption Spectroscopy of Synthetic Minerals

et al. 2020

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“…Recently, several studies have employed microfocus X-ray fluorescence chemical mapping to visualize either the chemical stratigraphy or micro-fabric of complex multi-phase materials, including Fe-Mn oxide. Spatial resolution of the X-ray mapping vary from 100 to 1 μm Marini et al, 2019;Sipos et al, 2016;Tharalson et al, 2019;Usui et al, 2017) depending on the X-ray source. Particularly, to visualize fine-scale chemical stratigraphy on the cm-sized nodules, an X-ray source with a visual resolution in the order of 100 μm is the most suitable.…”

Section: Introductionmentioning

confidence: 99%

Fine‐scale chemostratigraphy of cross‐sectioned hydrogenous ferromanganese nodules from the western North Pacific

et al. 2021

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A broad area densely covered by ferromanganese nodules was recently discovered around Minamitorishima (Marcus) Island, representing a high-potential metal resource, particularly for Co, Ni, Mo, and W. We studied 16 nodule samples from nodule fields around Minamitorishima Island. To define the fine-scale chemostratigraphy of the nodules, polished cross-sections of the samples were analyzed by microfocus X-ray fluorescence. Our results show that a general pattern of compositional variation was common throughout the growth history of the nodules in all the regions we studied.Chemical mapping clarified changes in the chemical signature and proportion of five lithological components throughout the growth history: Mn represented columnar δ-MnO 2 ; Fe represented layered amorphous FeOOH*xH 2 O; Ti represented TiO 2 *2H 2 O intergrown with an amorphous FeOOH phase; P, Ca and Y represented particles of biogenic calcium phosphate; and Si, Al, K, Cu, and Ni represented pelagic sediment infills. We proposed a method for a creating a multi-dimensional compositional map of the fine-scale chemostratigraphy observed in the ferromanganese oxide layers on the basis of merging the mapped Mn, Fe, Ti, P, Si and Cu intensities. Multidimensional compositional mapping of the sampled nodules from the western North Pacific revealed two fundamental findings: (1) previously recognized first-order Fe-Mn layers, L0, L1, and L2, were further divided into two, three, and four sublayers, respectively, and (2) a delayed supply of material to be nuclei of nodule or a growth hiatus of Fe-Mn layer(s), leading to missing sublayers in the layers L0 and L2, regulated the nodule size. In contrast, layer L1, which does not have any missing sublayers, was commonly observed in the samples for this study and has been reported in studies of other regions in the western Pacific. We propose, therefore, that the layer L1 is a key facies for examining chemostratigraphic correlations with other areas of seafloor.

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“…This is even more true with synchrotron techniques where the beam can be typically focused in a micrometric-sized spot, thus accessing a scale which can be relevant for materials in the battery field. As in part mentioned in the other sections, it is possible to map samples with XRD 39,40 , XPS 115 , X-ray fluorescence (XRF) 126 or infrared, usually with resolution in the micrometer range. In this section the most widespread techniques will be discussed, mostly related to the classical radiography, which bases its contrast on the variable absorption of a physical object in the space.…”

Section: Imaging Techniquesmentioning

confidence: 99%

Synchrotron radiation based operando characterization of battery materials

et al. 2023

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Combined micro X-ray absorption and fluorescence spectroscopy to map phases of complex systems: the case of sphalerite

Cited by 8 publications

References 31 publications

The State of Trace Elements (In, Cu, Ag) in Sphalerite Studied by X-Ray Absorption Spectroscopy of Synthetic Minerals

The State of Trace Elements (In, Cu, Ag) in Sphalerite Studied by X-Ray Absorption Spectroscopy of Synthetic Minerals

Fine‐scale chemostratigraphy of cross‐sectioned hydrogenous ferromanganese nodules from the western North Pacific

Synchrotron radiation based operando characterization of battery materials

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