Iron local structure in tektites and impact glasses by extended X-ray absorption fine structure and high-resolution X-ray absorption near-edge structure spectroscopy

Giuli, Gabriele; Pratesi, Giovanni; Cipriani, Curzio; Paris, Eleonora

doi:10.1016/s0016-7037(02)01030-x

Cited by 86 publications

(83 citation statements)

References 27 publications

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“…Overall, these results confirm that Fe in the melt glasses is predominantly 4-coordinate Fe(II). The bond lengths observed for the melt glasses and tektite are near the endpoints of the previously reported range for tektites collected from various strewnfields [52,63].…”

supporting

confidence: 70%

“…2 (right). XANES studies of Fe-bearing minerals and glasses, including waste-form glasses and fallout collected from the Trinity test [50][51][52][53][54][55][56][57], often use the centroid of the pre-edge peaks (after isolation from the background) to quantitatively determine the Fe(II)/(Fe(II) + Fe(III)) fraction. The results of applying this procedure to our dataset are shown in Fig.…”

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confidence: 99%

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Chemical speciation of U, Fe, and Pu in melt glass from nuclear weapons testing

Pacold

Lukens

Booth

et al. 2016

Journal of Applied Physics

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Nuclear weapons testing generates large volumes of glassy material that influence the transport of dispersed actinides in the environment and may carry information on the composition of the detonated device. We determine the oxidation state of U and Fe (which is known to buffer the oxidation state of actinide elements and to affect the redox state of groundwater) in samples of melt glass collected from three U.S. nuclear weapons tests. For selected samples, we also determine the coordination geometry of U and Fe, and we report the oxidation state of Pu from one melt glass sample. We find significant variations among the melt glass samples, and in particular, find a clear deviation in one sample from the expected buffering effect of Fe(II)/Fe(III) on the oxidation state of uranium. In the first direct measurement of Pu oxidation state in a nuclear test melt glass, we obtain a result consistent with existing literature that proposes Pu is primarily present as Pu(IV) in post-detonation material. In addition, our measurements imply that highly mobile U(VI) may be produced in significant quantities when melt glass is quenched rapidly following a nuclear detonation, though these products may remain immobile in the vitrified matrices. The observed differences in chemical state among the three samples show that redox conditions can vary dramatically across different nuclear test conditions. The local soil composition, associated device materials, and the rate of quenching are all likely to affect the final redox state of the glass. The resulting variations in glass chemistry are significant for understanding and interpreting debris chemistry, and the later environmental mobility of dispersed material.

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confidence: 70%

mentioning

confidence: 99%

Chemical speciation of U, Fe, and Pu in melt glass from nuclear weapons testing

Pacold

Lukens

Booth

et al. 2016

Journal of Applied Physics

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“…However, when the radii of the substituting cations are not different significantly from iron cations (see for the radii of Fe, Cr, Mn, CO and Ni cations [39] in Table 2), even Rietveld refinement of the XRD data cannot provide convincible evidences to determine the occupation of the incorporated metals whereas XANES spectra could be useful by evaluating the pre-edge peak. Pre-edge peak represents an sed like transition and is thus dipole-forbidden, but becomes partially allowed by the hybridization of the d-states of the transition metal with surrounding atoms [40,41]. It can be observed that the intensity of the pre-edge peak varies with the coordination environment.…”

Section: Occupying Sites Of Substituting Metalsmentioning

confidence: 99%

The valence and site occupancy of substituting metals in magnetite spinel structure Fe3−xMxO4 (M = Cr, Mn, Co and Ni) and their influence on thermal stability: An XANES and TG-DSC investigation

Liang

Zhong

Zhu

et al. 2013

Solid State Sciences

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“…Most research on local structure of impact products considers either coordination number or oxidation state based on analysis and comparison of pre -edge features, but combined analyses of EXAFS, Fe -O bonds, and distance are rare. Giuli et al (2002) was the first study to incorporate the results of XANES and EXAFS in tektites and impact glass, and summarize the local structures of Fe. This manuscript includes a study on more tektites and impact glass samples that compliments data in the study cited earlier.…”

Section: Introductionmentioning

confidence: 99%

Local structure of iron in tektites and natural glass: An insight through X-ray absorption fine structure spectroscopy

Wang¹,

Yoshiasa²,

Okube

et al. 2013

Journal of Mineralogical and Petrological Sciences

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The local structure of iron in tektites from six strewn fields, and impact -and non -impact -related glass were studied using the Fe K -edge X -ray absorption near edge structure (XANES) and extended X -ray absorption fine structure (EXAFS) techniques, in order to obtain quantitative data on Fe -O bond length and Fe coordination number. X -ray absorption fine structure (XAFS) spectra and Fe -O bonds in standard minerals such as hematite, fayalite, and magnetite were compared. The degree of oxidation was measured based on the valencies of iron in the samples. Tektites contain a greater proportion of ferrous than ferric iron [0.04 (1) /ƩFe] are higher than that in tektites. Based on the measured Fe -O distance, it was inferred that 4 -and 5 -coordinated Fe exist in tektites, whereas volcanic glass contains 5 -and 6 -coordinated Fe. Impact -related glass possesses various local structures caused by the combination of 4 -, 5 -, and 6 -coordinated Fe. During formation, tektites experience high temperatures and a reducing atmosphere when they were ejected into the outer space. In contrast, the impact -related glass, which was ejected into the atmosphere or which remained close to the crater, experienced a more complex environment, with air pressure, density, and temperature varying across the atmospheric layers. Thus, impact -related glass presents more complicated oxidation states and structure compared to tektites. Volcanic glass, on the other hand, has a relatively stable redox condition; and thus, it undergoes only a small change in the degree of oxidation. This study indicates that the local structure and oxidation state of Fe may change due to the environment that the glass experienced during its formation. These different kinds of natural glass can be distinguished from each other using the study of the local structure.

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Iron local structure in tektites and impact glasses by extended X-ray absorption fine structure and high-resolution X-ray absorption near-edge structure spectroscopy

Cited by 86 publications

References 27 publications

Chemical speciation of U, Fe, and Pu in melt glass from nuclear weapons testing

Chemical speciation of U, Fe, and Pu in melt glass from nuclear weapons testing

The valence and site occupancy of substituting metals in magnetite spinel structure Fe3−xMxO4 (M = Cr, Mn, Co and Ni) and their influence on thermal stability: An XANES and TG-DSC investigation

Local structure of iron in tektites and natural glass: An insight through X-ray absorption fine structure spectroscopy

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