Molecular structure of the uranyl mineral uranopilite—a Raman spectroscopic study

Frost, Ray L.; Carmody, Onuma; Erickson, Kristy L.; Weier, Matt L.; Henry, Dermot A.; Čejka, Jiří

doi:10.1016/j.molstruc.2004.08.014

Cited by 50 publications

(26 citation statements)

References 22 publications

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“…From the TG curve of uranopilite it may be inferred that uranopilite contains structurally nonequivalent water molecules. This supports conclusion from X-ray single crystal structure analysis, infrared and Raman spectroscopy (Frost et al, 2004a). Thermal decomposition of uranopilite proceeds in a set of partly overlapping steps, dehydration, dehydroxylation, and decomposition of anhydrous intermediates.…”

Section: Discussionsupporting

confidence: 88%

An XRD, SEM and TG study of a uranopilite from Australia

Frost¹,

Weier²,

Ayoko³

et al. 2006

Mineral. mag.

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A uranopilite from The South Alligator River, Northern Territory, Australia has been studied using X-ray diffraction, scanning electron microscopy with EDAX attachment and thermogravimetry in conjunction with evolved gas mass spectrometry. X-ray diffraction shows the mineral is a pure uranopilite with little or no impurities. SEM images show the uranopilite to consist of long elongated crystals up to 50 μm in length and 5 μm in width. Thermogravimetry combined with mass spectrometry shows that dehydration occurs around 31 °C resulting in the formation of metauranopilite. The first dehydration step over 20 -71 °C corresponds to the decrease of 5.4 wt %, equivalent to 6.076 H 2 O. The second dehydration step over 71-162.4 °C corresponds to a decrease of 4.7 wt % equivalent to 5.288 H 2 O making a total of 11.364 moles of H 2 O, close to 12 H 2 O for uranopilite. Dehydroxylation takes place over the temperature range 80 to 160 °C. The loss of sulphate occurs at higher temperatures in two steps at 622 and 636 °C. A mass loss also occurs at 755 °C accounted for by evolved oxygen.

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Section: Discussionsupporting

confidence: 88%

An XRD, SEM and TG study of a uranopilite from Australia

Frost¹,

Weier²,

Ayoko³

et al. 2006

Mineral. mag.

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“…Spectra at liquid nitrogen temperature were obtained using a Linkam thermal stage (Scientific Instruments Ltd, Waterfield, Surrey, England). Details of the technique have been published by the authors [14][15][16][17].…”

Section: Raman Microprobe Spectroscopymentioning

confidence: 99%

Raman spectroscopic study of the molecular structure of the uranyl mineral zippeite from Jáchymov (Joachimsthal), Czech Republic

Frost

Čejka

Boström

et al. 2007

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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(2007) Raman spectroscopic study of the molecular structure of the uranyl mineral zippeite from Jáchymov (Joachimsthal), Czech Republic. Spectrochimica Acta Part A 67(5):1220 -1227. ) Å. Calculated U-O bond lengths are in agreement with U-O bond lengths from the single crystal structure analysis and those inferred for uranyl anion sheet topology of uranyl pentagonal dipyramidal coordination polyhedra. The number of observed bands supports the conclusion from single crystal structure analysis that at least two symmetrically distinct U 6+ (in uranyls) and S 6+ (in sulfates), water molecules and hydroxyls may be present in the crystal structure of the zippeite studied. Strong to very weak hydrogen bonds present in the crystal structure of zippeite studied were inferred from the IR spectra. Copyright 2007 Elsevier

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Section: Raman Microprobe Spectroscopymentioning

confidence: 99%

Raman spectroscopy of dawsonite NaAl(CO₃)(OH)₂

Frost

Bouzaid

2007

J Raman Spectroscopy

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Raman spectroscopy at both 298 and 77 K complimented with infrared spectroscopy has been used to study the structure of dawsonite. Previous crystallographic studies concluded that the structure of dawsonite was a simple one, however both Raman and infrared spectroscopy show that this conclusion is incorrect. Multiple bands are observed in both the Raman and infrared spectra in the antisymmetric stretching and bending regions showing that the symmetry of the carbonate anion is reduced and in all probablity the carbonate anions are not equivalent in the dawsonite structure. Multiple OH deformation vibrations centred upon 950 cm -1 in both the Raman and infrared spectra show that the OH units in the dawsonite structure are non-equivalent. Calculations using the position of the Raman and infrared OH stretching vibrations enabled estimates of the hydrogen bond distances of 0.2735, 0.27219 pm at 298 K and 0.27315, 0.2713 pm at 77 K to be made. This indicates strong hydrogen bonding of the OH units in the dawsonite structure.

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Molecular structure of the uranyl mineral uranopilite—a Raman spectroscopic study

Cited by 50 publications

References 22 publications

An XRD, SEM and TG study of a uranopilite from Australia

An XRD, SEM and TG study of a uranopilite from Australia

Raman spectroscopic study of the molecular structure of the uranyl mineral zippeite from Jáchymov (Joachimsthal), Czech Republic

Raman spectroscopy of dawsonite NaAl(CO₃)(OH)₂

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Molecular structure of the uranyl mineral uranopilite—a Raman spectroscopic study

Cited by 50 publications

References 22 publications

An XRD, SEM and TG study of a uranopilite from Australia

An XRD, SEM and TG study of a uranopilite from Australia

Raman spectroscopic study of the molecular structure of the uranyl mineral zippeite from Jáchymov (Joachimsthal), Czech Republic

Raman spectroscopy of dawsonite NaAl(CO3)(OH)2

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Raman spectroscopy of dawsonite NaAl(CO₃)(OH)₂