Capturing ammonium nitrate in a synthetic uranium oxide hydrate phase: revealing the role of ammonium ions and anion inclusions.

Although uranium oxide hydrate (UOH) minerals and synthetic phases have been extensively studied, the role of ammonium ions in the formation of UOH materials is not well understood. In this work, the stabilization of a synthetic UOH phase with ammonium ions and the inclusion of ammonium nitrate were investigated using a range of structural and spectroscopic techniques. Compound (NH)(NO)[(UO)O(OH)] (U-N1) crystallises in the orthorhombic 2 space group, having a layered structure with typical α-UO type layers and interlayer (NH) cations as well as (NO) anions.

One of Nature's Puzzles Is Assembled: Analog of the Earth's Most Complex Mineral, Ewingite, Synthesized in a Laboratory.

Through the combination of low-temperature hydrothermal synthesis and room-temperature evaporation, a synthetic phase similar in composition and crystal structure to the Earth's most complex mineral, ewingite, was obtained. The crystal structures of both natural and synthetic compounds are based on supertetrahedral uranyl-carbonate nanoclusters that are arranged according to the cubic body-centered lattice principle. The structure and composition of the uranyl carbonate nanocluster were refined using the data on synthetic material.

Hidden and apparent twins in uranyl-oxide minerals agrinierite and rameauite: a demonstration of metric and reticular merohedry.

In this work, the structures of chemically related uranyl-oxide minerals agrinierite and rameauite have been revisited and some corrections to the available structure data are provided. Both structures were found to be twinned. The two minerals are chemically similar, and though their structures differ considerably, their unit-cell metrics are similar.

Molybdenum Disorder in Hydrated Sedovite, Ideally U(MoO)·HO, a Microporous Nanocrystalline Mineral Characterized by Three-Dimensional Electron Diffraction, Density Functional Theory Computations, and Complexity Analysis.

Sedovite, U(MoO)·HO, is reported as being one of the earliest supergene minerals formed of the secondary zone. The difficulty of isolating enough pure material limits studies to techniques that can access the nanoscale combined with theoretical analyses. The crystal structure of sedovite has been solved and refined using the dynamical approach from three-dimensional electron diffraction data collected on natural nanocrystals found among iriginite.

Crystal structure of the uranyl arsenate mineral hügelite, Pb(UO)O(AsO)(HO), revisited: a correct unit cell, twinning and hydrogen bonding.

Revisiting the structure of uranyl arsenate mineral hügelite provided some corrections to the available structural data. The previous twinning model (by reticular merohedry) in hügelite has been corrected. Twinning of the monoclinic unit cell [a = 7.

Hydrogen disorder in kaatialaite Fe[AsO(OH)]5HO from Jáchymov, Czech Republic: determination from low-temperature 3D electron diffraction.

Kaatialaite mineral Fe[AsO(OH)]5HO from Jáchymov, Czech Republic forms white aggregates of needle-shaped crystals with micrometric size. Its structure at ambient temperature has already been reported but hydrogen atoms could not be identified from single-crystal X-ray diffraction. An analysis using 3D electron diffraction at low temperature brings to light the hydrogen positions and the existence of hydrogen disorder.

Full crystal structure, hydrogen bonding and spectroscopic, mechanical and thermodynamic properties of mineral uranopilite.

The determination of the full crystal structure of the uranyl sulfate mineral uranopilite, (UO)(SO)O(OH)·14HO, including the positions of the hydrogen atoms within the corresponding unit cell, has not been feasible to date due to the poor quality of its X-ray diffraction pattern. In this paper, the complete crystal structure of uranopilite is established for the first time by means of first principles solid-state calculations based in density functional theory employing a large plane wave basis set and pseudopotential functions. The computed unit-cell parameters and structural data for the non-hydrogen atoms are in excellent agreement with the available experimental data.

Hydrogen bonding in the crystal structure of phurcalite, Ca[(UO)O(PO)]·7HO: single-crystal X-ray study and TORQUE calculations.

The crystal structure of phurcalite, Ca[(UO)O(PO)]·7HO, orthorhombic, a = 17.3785 (9) Å, b = 15.9864 (8) Å, c = 13.

Crystal Structure, Infrared Spectrum and Elastic Anomalies in Tuperssuatsiaite.

The full crystal structure of the phyllosilicate mineral tuperssuatsiaite, including the positions of the hydrogen atoms in its unit cell, is determined for the first time by using first-principles solid-state methods. From the optimized structure, its infrared spectrum and elastic properties are determined. The computed infrared spectrum is in excellent agreement with the experimental spectrum recorded from a natural sample from Ilímaussaq alkaline complex (Greenland, Denmark).

The magnesium uranyl tricarbonate octadecahydrate mineral, bayleyite: Periodic DFT study of its crystal structure, hydrogen bonding, mechanical properties and infrared spectrum.

Bayleyite is a highly hydrated uranyl tricarbonate mineral containing eighteen water molecules per formula unit. Due to this large water content, the correct description of its crystal structure is a great challenge for the first principles solid state methodology. In this work, the crystal structure, hydrogen bonding, mechanical properties and infrared spectrum of bayleyite, Mg[UO(CO)] · 18 HO, have been investigated by means of Periodic Density Functional Theory methods using plane wave basis sets and pseudopotentials.

Structural, mechanical, spectroscopic and thermodynamic characterization of the copper-uranyl tetrahydroxide mineral vandenbrandeite.

The full crystal structure of the copper-uranyl tetrahydroxide mineral (vandenbrandeite), including the positions of the hydrogen atoms, is established by the first time from X-ray diffraction data taken from a natural crystal sample from the Musonoi Mine, Katanga Province, Democratic Republic of Congo. The structure is verified using first-principles solid-state methods. From the optimized structure, the mechanical and dynamical stability of vandenbrandeite is studied and a rich set of mechanical properties are determined.

The layered uranyl silicate mineral uranophane-β: crystal structure, mechanical properties, Raman spectrum and comparison with the α-polymorph.

The crystal structure, elastic properties and the Raman spectrum of the layered calcium uranyl silicate pentahydrate mineral uranophane-β, Ca(UO2)2Si2O6(OH)2·5H2O, are studied by means of first-principles solid-state methods and compared with the corresponding information for the α polymorph. The availability of the energy optimized full crystal structure of uranophane-β, including the positions of the hydrogen atoms, made possible the computation of its elastic properties and the Raman spectrum by using the theoretical methodology. An extended set of relevant mechanical data is reported.

Crystal structure of vyacheslavite, U(PO)(OH), solved from natural nanocrystal: a precession electron diffraction tomography (PEDT) study and DFT calculations.

The crystal structure of the U(iv)-phosphate mineral vyacheslavite has been solved from precession electron diffraction tomography (PEDT) data from the natural nano-crystal and further refined using density-functional theory (DFT) calculations. Vyacheslavite is orthorhombic, with the space group , with ≈ 6.96 Å, ≈ 9.

Crystal structure, hydrogen bonding, mechanical properties and Raman spectrum of the lead uranyl silicate monohydrate mineral kasolite.

The crystal structure, hydrogen bonding, mechanical properties and Raman spectrum of the lead uranyl silicate monohydrate mineral kasolite, Pb(UO)(SiO)·HO, are investigated by means of first-principles solid-state methods based on density functional theory using plane waves and pseudopotentials. The computed unit cell parameters, bond lengths and angles and X-ray powder pattern of kasolite are found to be in very good agreement with their experimental counterparts. The calculated hydrogen atom positions and associated hydrogen bond structure in the unit cell of kasolite confirmed the hydrogen bond scheme previously determined from X-ray diffraction data.

Revealing hydrogen atoms in a highly-absorbing material: an X-ray diffraction study and Torque method calculations for lead-uranyl-oxide mineral curite.

The crystal structure of lead uranyl-oxide hydroxy-hydrate mineral curite, ideally Pb(HO)[(UO)O(OH)], was studied by means of single-crystal X-ray diffraction and theoretical calculations in order to localize positions of hydrogen atoms in the structure. This study has demonstrated that hydrogen atoms can be localized successfully also in materials for which the conventional approach of structure analysis failed, here due to very high absorption of X-rays by the mineral matrix. The theoretical calculations, based on the Torque method, provide a robust, fast real-space method for determining HO orientations from their rotational equilibrium condition.

Nollmotzite, Mg[U(UO)OF]·4HO, the first natural uranium oxide containing fluorine.

Nollmotzite (IMA2017-100), Mg[U(UO)FO](HO), is a new uranium oxide fluoride mineral found in the Clara mine, Black Forest Mountains, Germany. Electron microprobe analysis provided the empirical formula (MgCu)[U(UO)OF][(HO)(OH)] based on three U and 15 O + F atoms per formula unit. Nollmotzite is monoclinic, space group Cm, with a = 7.

A commensurately modulated structure of parabutlerite, FeSO(OH)·2HO.

Parabutlerite, orthorhombic FeSO(OH)·2HO, has been reinvestigated using single-crystal X-ray diffraction. The structure of parabutlerite is commensurately modulated, with a = 20.0789 (8), b = 7.

Could incommensurability in sulfosalts be more common than thought? The case of meneghinite, CuPbSbS.

The structure of meneghinite (CuPbSbS), from the Bottino mine in the Apuan Alps (Italy), has been solved and refined as an incommensurate structure in four-dimensional superspace. The structure is orthorhombic, superspace group Pnma(0β0)00s, cell parameters a = 24.0549 (3), b = 4.

Arsenic-rich acid mine water with extreme arsenic concentration: mineralogy, geochemistry, microbiology, and environmental implications.

Extremely arsenic-rich acid mine waters have developed by weathering of native arsenic in a sulfide-poor environment on the 10th level of the Svornost mine in Jáchymov (Czech Republic). Arsenic rapidly oxidizes to arsenolite (As2O3), and there are droplets of liquid on the arsenolite crust with high As concentration (80,000-130,000 mg·L(-1)), pH close to 0, and density of 1.65 g·cm(-1).

Raman spectroscopic study of the hydroxy-phosphate mineral plumbogummite PbAl₃(PO₄)₂(OH,H₂O)₆.

Plumbogummite PbAl(3)(PO(4))(2)(OH,H(2)O)(6) is a mineral of environmental significance and is a member of the alunite-jarosite supergroup. The molecular structure of the mineral has been investigated by Raman spectroscopy. The spectra of different plumbogummite specimens differ although there are many common features.

A vibrational spectroscopic study of hydrated Fe(3+) hydroxyl-sulfates; polymorphic minerals butlerite and parabutlerite.

Raman and infrared spectra of two polymorphous minerals with the chemical formula Fe3+(SO4)(OH)·2H2O, monoclinic butlerite and orthorhombic parabutlerite, are studied and the spectra assigned. Observed bands are attributed to the (SO4)2- stretching and bending vibrations, hydrogen bonded water molecules, stretching and bending vibrations of hydroxyl ions, water librational modes, Fe-O and Fe-OH stretching vibrations, Fe-OH bending vibrations and lattice vibrations. The O-H⋯O hydrogen bond lengths in the structures of both minerals are calculated from the wavenumbers of the stretching vibrations.

Raman spectroscopic study of a hydroxy-arsenate mineral containing bismuth-atelestite Bi2O(OH)(AsO4).

The Raman spectrum of atelestite Bi2O(OH)(AsO4), a hydroxy-arsenate mineral containing bismuth, has been studied in terms of spectra-structure relations. The studied spectrum is compared with the Raman spectrum of atelestite downloaded from the RRUFF database. The sharp intense band at 834 cm(-1) is assigned to the ν1 AsO4(3-) (A1) symmetric stretching mode and the three bands at 767, 782 and 802 cm(-1) to the ν3 AsO4(3-) antisymmetric stretching modes.

Raman spectroscopic study of the uranyl sulphate mineral zippeite: low wavenumber and U-O stretching regions.

The uranyl sulphate mineral zippeite was studied by Raman spectroscopy. The phase purity of the sample was initially checked by X-ray powder diffraction and its chemical composition was defined by electron microprobe (wavelength dispersive spectroscopy, WDS) analysis. The Raman spectroscopy research focused on the low wavenumber and uranyl stretching vibration regions.