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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Alkali Metal Cation Effects on Dinitrogen Complexes and Organometallic Compounds

Alkali metal (AM) cations are often taken for granted as counterions in coordination chemistry and organometallic reactions. However, the AM cation can be more than a bystander in inorganic transformations. This Account focuses on research that has elucidated several types of AM cation effects and how these can be exploited to achieve novel structures and reactivity pathways. Here, a particular focus is on AM cation effects in low-coordinate iron β-diketiminate complexes, though we address general trends and potential applications in systems with other supporting ligands.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Stabilization of Th{sup 3+} ions into mixed-valence thorium fluoride

The unusual oxidation state +3 of the thorium has been stabilized into a lithium containing non-stoichiometric mixed-valence (III/IV) thorium fluorinated phase with formula Li{sub 2+x}Th{sub 12}F{sub 50} (0<x<1.8). This phase is closely related to the Li{sub 5.5}Ce{sub 12}F{sub 50} one, the structure of which has been determined from the combined single-crystal X-ray diffraction and high resolution synchrotron powder diffraction. In these phases, the Li{sup +} ions can be divided into two groups and are located either in locked positions or in open channels of the three dimensional framework. The amount of Li{sup +} ions in open channels can be variable, so that the afore mentioned single phase may be considered as an insertion compound. The Li{sup +} insertion is accompanied by the simultaneous reduction of a part of the Th{sup 4+} ions, resulting in a mixed-valence III/IV thorium fluoride. The electrochemical insertion of Li{sup +} ions into the open channels of the host matrix has been carried out at 60 {sup o}C, using an alkylcarbonate PC-LiClO{sub 4} 1 M electrolyte. The Li{sup +} and Th{sup 3+} contents, both in the starting composition and the Li{sup +} inserted ones, were investigated by high resolution solid state {sup 7}Li NMR and EPR, respectively. -- Graphical abstract: Electrochemical insertion of Li{sup +} ions into mixed-valence III/IV thorium fluoride and EPR spectra for the raw and inserted compounds. Display Omitted

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2010

The study of the crystalline phosphates of kosnarite type structure containing different alkali metals

The incorporation possibilities of different alkali elements into crystalline phosphates A{sub 1-x}A'{sub x}Hf{sub 2}(PO{sub 4}){sub 3} (A=Li, Na, K, Rb, Cs) were studied, the formation regions of kosnarite solid solutions were determined. Na{sub 0.5}K{sub 0.5}Hf{sub 2}(PO{sub 4}){sub 3} crystal structure was studied by powder X-ray diffraction, and the distribution of alkali metals in kosnarite structure was found out. The phosphate crystallizes in the space group R3c, with a=8.7295(1) A, c=23.2023(4) A, V=1531.24(4) A{sup 3}, Z=6; R{sub wp}=6.15, R{sub p}=4.43. The concentration region knowledge of the kosnarite phase existence and peculiarities of their phase formation in the A{sub 1-x}A'{sub x}M{sub 2}(PO{sub 4}){sub 3} (M=Ti, Zr, Hf) systems allow us to choose phosphate matrice compositions suitable for solidification of reprocessing wastes of spent U-Pu nuclear fuels. - Graphical abstract: The incorporation possibilities of different alkali elements into crystalline phosphates A{sub 1-x}A'{sub x}Hf{sub 2}(PO{sub 4}){sub 3} (A=Li, Na, K, Rb, Cs) were studied, the formation regions of kosnarite solid solutions were determined. Na{sub 0.5}K{sub 0.5}Hf{sub 2}(PO{sub 4}){sub 3} crystal structure was studied by powder X-ray diffraction, and the distribution of alkali metals in kosnarite structure was found out. The phosphate crystallizes in the space group R3c, with a=8.7295(1) A, c=23.2023(4) A, V=1531.24(4) A{sup 3}, Z=6; R{sub wp}=6.15, R{sub p}=4.43. The concentration region knowledge of the kosnarite phase existence and peculiarities of their phase formation in the A{sub 1-x}A'{sub x}M{sub 2}(PO{sub 4}){sub 3} (M=Ti, Zr, Hf) systems allow us to choose phosphate matrice compositions suitable for solidification of reprocessing wastes of spent U-Pu nuclear fuels.

36 MATERIALS SCIENCE↗
DOE OSTI2011

High-pressure synthesis and crystal structure of the lithium borate HP-LiB{sub 3}O{sub 5}

The new lithium borate HP-LiB{sub 3}O{sub 5} was synthesized under high-pressure/high-temperature conditions of 6 GPa and 1050 deg. C in a multianvil press with a Walker-type module. The compound crystallizes in the space group Pnma (no. 62) with the lattice parameters a=829.7(2), b=759.6(2), and c=1726.8(4) pm (Z=16). The high-pressure compound HP-LiB{sub 3}O{sub 5} is built up from a three-dimensional network of BO{sub 4} tetrahedra and BO{sub 3} groups, which incorporates Li{sup +} ions in channels along the b-axis. Band assignments of measured IR- and Raman spectra were done via quantum-mechanical calculations. Additionally, the thermal behavior of HP-LiB{sub 3}O{sub 5} was investigated. - Graphical abstract: The new high-pressure compound HP-LiB{sub 3}O{sub 5} is built up from a three-dimensional network of BO4 tetrahedra and BO{sub 3} groups, which incorporates Li{sup +} ions in channels along the b-axis. In this paper, the synthesis, the crystal structure, and the properties of HP-LiB{sub 3}O{sub 5} are described. Highlights: > Synthesis of a new lithium borate with the composition HP-LiB{sub 3}O{sub 5} at high pressure. > In contrast to the non-centrosymmetric phase LiB{sub 3}O{sub 5}, this high-pressure phase is centrosymmetric. > First example of ternary alkali borates exhibiting threefold bridging oxygen atoms.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

A{sub 2}TiF{sub 5}.nH{sub 2}O (A=K, Rb, or Cs; n=0 or 1): Synthesis, structure, characterization, and calculations of three new uni-dimensional titanium fluorides

Three new uni-dimensional alkali metal titanium fluoride materials, A{sub 2}TiF{sub 5}.nH{sub 2}O (A=K, Rb, or Cs; n=0 or 1) have been synthesized by hydrothermal reactions. The structures of A{sub 2}TiF{sub 5}.nH{sub 2}O have been determined by single-crystal X-ray diffraction. The Ti{sup 4+} cations have been reduced to Ti{sup 3+} during the synthesis reactions. All three A{sub 2}TiF{sub 5}.nH{sub 2}O materials contain novel 1-D chain structures that are composed of the slightly distorted Ti{sup 3+}F{sub 6} corner-sharing octahedra attributable to the Jahn-Teller distortion. The coordination environment of the alkali metal cations plays an important role to determine the degree of turning in the chain structures. Complete structural analyses, Infrared and UV-vis diffuse reflectance spectra, and thermal analyses are presented, as are electronic structure calculations. -- Graphical abstract: Ball-and-stick and polyhedral representations for (a) {beta}-K{sub 2}TiF{sub 5} and (b) Rb{sub 2}TiF{sub 5}.H{sub 2}O or Cs{sub 2}TiF{sub 5}.H{sub 2}O with the K{sup +} and Rb{sup +} (or Cs{sup +}) coordination environment emphasized. Display Omitted Research highlights: > Synthesis, structure, characterization, and calculation of new titanium fluorides. > Study of reduction of starting Ti{sup 4+} cations to Ti{sup 3+} by DMF. > Novel 1-D chain structures with Jahn-Teller distorted TiF{sub 6} octahedra.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Alkali metal cation complexation by 1,3-alternate, mono-ionisable calix[4]arene-benzocrown-6 compounds

Alkali metal cation extraction behavior for two series of 1,3-alternate, mono-ionizable calix[4]arene-benzocrown-6 compounds is examined. In Series 1, the proton-ionizable group is a substituent on the benzo group of the polyether ring that directs it away from the crown ether cavity. In Series 2, the proton-ionizable group is attached to one para position in the calixarene framework, thus positioning it over the crown ether ring. Competitive solvent extraction of alkali metal cations from aqueous solutions into chloroform shows high Cs+ efficiency and selectivity. Single-species extraction pH profiles of Cs+ for Series 1 and 2 ligands with the same proton-ionizable group are very similar. Thus, association of Cs+ with the calixcrown ring is more important than the the proton-ionizable group’s position in relation to the crown ether cavity. Solid-state structures are presented for two unionized ligands from Series 2, as is a crystal containing two different ionized ligand–Cs+ complexes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Chloride substitution in sodium borohydride

The dissolution of sodium chloride and sodium borohydride into each other resulting in formation of solid solutions of composition Na(BH{sub 4}){sub 1-x}Cl{sub x} is studied. The dissolution reaction is facilitated by two methods: ball milling or combination of ball milling and annealing at 300 deg. C for three days of NaBH{sub 4}-NaCl samples in molar ratios of 0.5:0.5 and 0.75:0.25. The degree of dissolution is studied by Rietveld refinement of synchrotron radiation powder X-ray diffraction (SR-PXD) data. The results show that dissolution of 10 mol% NaCl into NaBH{sub 4}, forming Na(BH{sub 4}){sub 0.9}Cl{sub 0.1}, takes place during ball milling. A higher degree of dissolution of NaCl in NaBH{sub 4} is obtained by annealing resulting in solid solutions containing up to 57 mol% NaCl, i.e. Na(BH{sub 4}){sub 0.43}Cl{sub 0.57}. In addition, annealing results in dissolution of 10-20 mol% NaBH{sub 4} into NaCl. The mechanism of the dissolution during annealing and the decomposition pathway of the solid solutions are studied by in situ SR-PXD. Furthermore, the stability upon hydrogen release and uptake were studied by Sieverts measurements. - Graphical Abstract: Dissolution of sodium chloride and sodium borohydride into each other resulting in formation of solid solutions of composition Na(BH{sub 4}){sub 1-x}Cl{sub x} is studied. Dissolution is facilitated by two methods: ball milling or annealing at 300 deg. C for three days of NaBH{sub 4}-NaCl samples. Sample compositions and dissolution mechanism are studied by Rietveld refinement of synchrotron radiation powder X-ray diffraction data. Highlights: > Studies of dissolution of sodium chloride and sodium borohydride into each other. > Solid state diffusion facilitated by mechanical and thermal treatments. > Dissolution is more efficiently induced by heating than by mechanical treatment. > Mechanism for dissolution studied by Rietveld refinement of in situ SR-PXD data.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2010

In situ X-ray absorption spectroscopic investigation of the electrochemical conversion reactions of CuF{sub 2}-MoO{sub 3} nanocomposite

We have used X-ray absorption spectroscopy at the Cu K-edge to investigate the electrochemical conversion reaction of 20 nm size 85 wt% CuF{sub 2}-15 wt% MoO{sub 3} nanocomposite under in situ conditions. The nanocomposite was prepared by high energy milling. Upon discharge, the lithiation reaction with the nanocomposite resulted in the formation of nanophase metallic Cu, which is consistent with the conversion of CuF{sub 2} into Cu and LiF. Based on XANES and Fourier transforms of EXAFS spectra, we show that the discharge process proceeded via the formation of highly dispersed Cu particles. Based on the coordination number of the first shell of Cu, the average size of the Cu particles was estimated to be in the 1-3 nm range in the fully discharged state. -- Graphical Abstract: Comparison of Fourier transform of in situ Cu K-edge EXAFS spectra for a fully discharged CuF{sub 2{center_dot}}MoO{sub 3} nanocomposite in a nonaqueous Li cell with that of a Cu foil. Quantitative analysis of the Fourier transforms confirmed that the discharge mechanism for the nanocomposite proceeds via the reaction CuF{sub 2}+2Li{yields}Cu+2LiF. The discharge product of Cu is in the form of highly dispersed nanoparticles. Display Omitted

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2011

Simulation and experimental study on compositional evolution of Li-Co in LiCoO{sub 2} thin films during sputter deposition

The compositional evolution in sputter deposited LiCoO{sub 2} thin films is influenced by process parameters involved during deposition. The electrochemical performance of these films strongly depends on their microstructure, preferential orientation and stoichiometry. The transport process of sputtered Li and Co atoms from the LiCoO{sub 2} target to the substrate, through Ar plasma in a planar magnetron configuration, was investigated based on the Monte Carlo technique. The effect of sputtering gas pressure and the substrate-target distance (d{sub st}) on Li/Co ratio, as well as, energy and angular distribution of sputtered atoms on the substrate were examined. Stable Li/Co ratios have been obtained at 5 Pa pressure and d{sub st} in the range 5-11 cm. The kinetic energy and incident angular distribution of Li and Co atoms reaching the substrate have been found to be dependent on sputtering pressure. Simulations were extended to predict compositional variations in films prepared at various process conditions. These results were compared with the composition of films determined experimentally using x-ray photoelectron spectroscopy (XPS). Li/Co ratio calculated using XPS was in moderate agreement with that of the simulated value. The measured film thickness followed the same trend as predicted by simulation. These studies are shown to be useful in understanding the complexities in multicomponent sputtering.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Ligation Kinetics as a Probe for Non-Covalent Electrostatic Bonding and Electron Solvation of Alkali and Alkaline Earth Cations with Ammonia

Mono-ligation kinetics were measured for ammonia reacting with atomic cations in the first two groups of the periodic table (K{sup +}, Rb{sup +}, Cs{sup +} and Ca{sup +}, Sr{sup +}, Ba{sup +}). Also, mono-ligation energies were computed using density functional theory (DFT) in an attempt to assess the role of non-covalent electrostatic interactions in these chemical reactions. The measurements were performed at room temperature in helium bath gas at 0.35 Torr using an inductively coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer. Rate coefficients are reported for ammonia addition, the only reaction channel that was observed with all these cations. A systematic decrease in the rate of addition of NH{sub 3} was observed for both group 1 and 2 cations going down the periodic table. The computational studies predict a decrease in the adduct binding energy and an increase in the bond separation going down groups 1 and 2 of the periodic table and provide some insight into the role of the extra selectron in the group 2 radical cations in ligand bonding. A correlation is seen between the efficiency of ligation and the binding energy of the adduct ion and attributed to the lifetime of the intermediate encounter complex against back dissociation which is dependent on its well depth. Higher-order additions of ammonia were also observed. Remarkable differences in the extent and kinetics were seen between the group 1 and 2 cations, and these were attributed to the occurrence of ammonia solvation of the extra s electron in the higher-order adducts of the alkaline earth cations. .

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2010

Super-radiance in the sodium resonance lines from sodium iodide arc lamps

Super-radiance observed within the centers of the sodium resonance D lines emitted by arc lamps containing sodium iodide as additive in a high-pressure mercury plasma environment was studied by high-resolution emission spectroscopy. The spectral radiance of these self-reversed lines including super-radiance was simulated by considering a local enhancement of the source function due to the presence of an additional source of radiation near the arc wall. Causes of this hitherto unrecognized source of radiation are given.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2012

Synthesis, structure, and optical properties of CsU{sub 2}(PO{sub 4}){sub 3}

CsU{sub 2}(PO{sub 4}){sub 3} was synthesized in highest yield by the reaction in a fused-silica tube of U, P, and Se in a CsCl flux at 1273 K. It crystallizes with four formula units in space group P2{sub 1}/n of the monoclinic system in a new structure type. The structure of CsU{sub 2}(PO{sub 4}){sub 3} is composed of U and Cs atoms coordinated by PO{sub 4}{sup 3-} units in distorted octahedral arrangements. Each U atom corner shares with six PO{sub 4}{sup 3-} units. Each Cs atom face shares with one, edge shares with two, and corner shares with three PO{sub 4}{sup 3-} units. The structure shares some features with the sodium zirconium phosphate structure type. X-ray powder diffraction results demonstrate that the present CsU{sub 2}(PO{sub 4}){sub 3} compound crystallizes in a structure different from the previously reported {beta} Prime - and {gamma}-CsU{sub 2}(PO{sub 4}){sub 3} compounds. CsU{sub 2}(PO{sub 4}){sub 3} is highly pleochroic, as demonstrated by single-crystal optical absorption measurements. - Graphical abstract: Stacking of the layers in CsU{sub 2}(PO{sub 4}){sub 3}, viewed along [100]. Highlights: Black-Right-Pointing-Pointer Compound CsU{sub 2}(PO{sub 4}){sub 3} crystallizes in a new structure type. Black-Right-Pointing-Pointer Structure shares some features with the sodium zirconium phosphate structure type. Black-Right-Pointing-Pointer CsU{sub 2}(PO{sub 4}){sub 3} is highly pleochroic, as demonstrated by single-crystal optical absorption measurements.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Operating The Upgraded NSTX HHFW Antenna Array In An Environment With Li-coated Surfaces

The single-feed, end-grounded straps of the NSTX 12-strap HHFW antenna array have been replaced with double-feed, center-grounded straps to reduce the voltages in the vicinity of the Faraday shield (FS) for a given strap current. The strap spacings to the FS and to the back plate were increased by 3 mm to decrease the electric fields for a given voltage. The electric fields near the FS have been roughly halved for the same strap currents, permitting a direct examination of the roles that internal fields play in determining antenna power limits in plasmas. Extensive RF/plasma conditioning of the antenna was required to remove enough of the evaporated Li deposits from prior wall conditioning to permit coupling in excess of 4 MW to L- and H-mode plasmas in 2009. Most arcs were associated with expulsion of Li from the FS/antenna frame surfaces. The center-grounded straps were less susceptible to arcing during ELMing H-mode plasmas. Reliable operation above 2 MW was difficult after the installation of the Liquid Lithium Divertor (LLD) in 2010. Li-compound 'dust' was found in the antennas after this run and is believed to have contributed to the reduced power limit.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Methods for synthesizing metal oxide nanowires

A method of synthesizing a metal oxide nanowire includes the steps of: combining an amount of a transition metal or a transition metal oxide with an amount of an alkali metal compound to produce a mixture; activating a plasma discharge reactor to create a plasma discharge; exposing the mixture to the plasma discharge for a first predetermined time period such that transition metal oxide nanowires are formed; contacting the transition metal oxide nanowires with an acid solution such that an alkali metal ion is exchanged for a hydrogen ion on each of the transition metal oxide nanowires; and exposing the transition metal oxide nanowires to the plasma discharge for a second predetermined time period to thermally anneal the transition metal oxide nanowires. Transition metal oxide nanowires produced using the synthesis methods described herein are also provided.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Syntheses and single-crystal structures of CsTh(MoO{sub 4}){sub 2}Cl and Na{sub 4}Th(WO{sub 4}){sub 4}

Colorless crystals of CsTh(MoO{sub 4}){sub 2}Cl and Na{sub 4}Th(WO{sub 4}){sub 4} have been synthesized at 993 K by the solid-state reactions of ThO{sub 2}, MoO{sub 3}, CsCl, and ThCl{sub 4} with Na{sub 2}WO{sub 4}. Both compounds have been characterized by the single-crystal X-ray diffraction. The structure of CsTh(MoO{sub 4}){sub 2}Cl is orthorhombic, consisting of two adjacent [Th(MoO{sub 4}){sub 2}] layers separated by an ionic CsCl sublattice. It can be considered as an insertion compound of Th(MoO{sub 4}){sub 2} and reformulated as Th(MoO{sub 4}){sub 2}.CsCl. The Th atom coordinates to seven monodentate MoO{sub 4} tetrahedra and one Cl atom in a highly distorted square antiprism. Na{sub 4}Th(WO{sub 4}){sub 4} adopts a scheelite superlattice structure. The three-dimensional framework of Na{sub 4}Th(WO{sub 4}){sub 4} is constructed from corner-sharing ThO{sub 8} square antiprisms and WO{sub 4} tetrahedra. The space within the channels is filled by six-coordinate Na ions. Crystal data: CsTh(MoO{sub 4}){sub 2}Cl, monoclinic, P2{sub 1}/c, Z=4, a=10.170(1) A, b=10.030(1) A, c=9.649(1) A, {beta}=95.671(2){sup o}, V=979.5(2) A{sup 3}, R(F)=2.65% for I>2{sigma}(I); Na{sub 4}Th(WO{sub 4}){sub 4}, tetragonal, I4{sub 1}/a, Z=4, a=11.437(1) A, c=11.833(2) A, V=1547.7(4) A{sup 3}, R(F)=3.02% for I>2{sigma}(I). -- Graphical abstract: The two-dimensional layered structure of CsTh(MoO{sub 4}){sub 2}Cl viewed down the b axis. Display Omitted Research highlights: {yields} Syntheses of CsTh(MoO{sub 4}){sub 2}Cl and Na{sub 4}Th(WO{sub 4}){sub 4} from chlorides. {yields} Single-crystal structures of CsTh(MoO{sub 4}){sub 2}Cl and Na{sub 4}Th(WO{sub 4}){sub 4}. {yields} CsTh(MoO{sub 4}){sub 2}Cl can be considered as an inclusion compound composed of covalent [Th(MoO{sub 4}){sub 2}] layer and ionic [CsCl] layers. {yields} Na{sub 4}Th(WO{sub 4}){sub 4} adopts a defect scheelite structure.

36 MATERIALS SCIENCE↗
DOE OSTI2011

From {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}O(MoO{sub 4}){sub 4}]{sup 6-} to {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})]{sup 6-} infinite chains in A{sub 6}U{sub 2}Mo{sub 4}O{sub 21} (A=Na, K, Rb, Cs) compounds: Synthesis and crystal structure of Cs{sub 6}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})]

A new caesium uranyl molybdate belonging to the M{sub 6}U{sub 2}Mo{sub 4}O{sub 21} family has been synthesized by solid-state reaction and its structure determined from single-crystal X-ray diffraction data. Contrary to the other alkali uranyl molybdates of this family (A=Na, K, Rb) where molybdenum atoms adopt only tetrahedral coordination and which can be formulated A{sub 6}[(UO{sub 2}){sub 2}O(MoO{sub 4}){sub 4}], the caesium compound Cs{sub 6}U{sub 2}Mo{sub 4}O{sub 21} should be written Cs{sub 6}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})] with molybdenum atoms in tetrahedral and square pyramidal environments. Cs{sub 6}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})] crystallizes in the triclinic symmetry with space group P1-bar and a=10.4275(14) A, b=15.075(2) A, c=17.806(2) A, {alpha}=70.72(1){sup o}, {beta}=80.38(1){sup o} and {gamma}=86.39(1){sup o}, V=2604.7(6) A{sup 3}, Z=4, {rho}{sub mes}=5.02(2) g/cm{sup 3} and {rho}{sub cal}=5.08(3) g/cm{sup 3}. A full-matrix least-squares refinement on the basis of F{sup 2} yielded R{sub 1}=0.0464 and wR{sub 2}=0.0950 for 596 parameters with 6964 independent reflections with I{>=}2{sigma}(I) collected on a BRUKER AXS diffractometer with Mo(K{alpha}) radiation and a CCD detector. The crystal structure of Cs compound is characterized by {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})]{sup 6-} parallels chains built from U{sub 2}O{sub 13} dimeric units, MoO{sub 4} tetrahedra and MoO{sub 5} square pyramids, whereas, Na, K and Rb compounds are characterized by {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}O(MoO{sub 4}){sub 4}]{sup 6-} parallel chains formulated simply of U{sub 2}O{sub 13} units and MoO{sub 4} tetrahedra. Infrared spectroscopy measurements using powdered samples synthesized by solid-state reaction, confirm the structural results. The thermal stability and the electrical conductivity are also studied. The four compounds decompose at low temperature (between 540 and 610 {sup o}C). -- Graphical abstract: The staking of {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})]{sup 6-} infinite uranyl molybdate ribbons in the Cs{sub 6}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})] structure. Display Omitted Highlights: {yields} Cs{sub 6}U{sub 2}Mo{sub 4}O{sub 2} a new compound with bidimensional crystal structure, characterized by infinite uranyl molybdate chains. {yields} Crystal structure similar to these of the compounds containing Na, K, Rb. {yields} Molybdenum atoms surrounded by five oxygen atoms to form an original and strongly distorted MoO{sub 5} environment. {yields} The chains arrangement illustrates the key role of the alkaline ionic radius, in the crystal structure distortion for Cs compound.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

The crystal chemistry of four thorium sulfates

Four thorium sulfate compounds have been synthesized and characterized. [Th(SO{sub 4}){sub 2}(H{sub 2}O){sub 7}].2H{sub 2}O (ThS1) crystallizes in space group P2{sub 1}/m, a=7.2488(4), b=12.1798(7), c=8.0625(5) A, {beta}=98.245(1){sup o}; Na{sub 10}[Th{sub 2}(SO{sub 4}){sub 9}(H{sub 2}O){sub 2}].3H{sub 2}O (ThS2), Pna2{sub 1}, a=17.842(2), b=6.9317(8), c=27.550(3) A; Na{sub 2}[Th{sub 2}(SO{sub 4}){sub 5}(H{sub 2}O){sub 3}].H{sub 2}O (ThS3), C2/c, a=16.639(2), b=9.081(1), c=25.078(3) A, {beta}= 95.322(2){sup o}; [Th{sub 4}(SO{sub 4}){sub 7}(OH){sub 2}(H{sub 2}O){sub 6}].2H{sub 2}O (ThS4), Pnma, a=18.2127(9), b=11.1669(5), c=14.4705(7) A. In all cases the Th cations are coordinated by nine O atoms corresponding to SO{sub 4} tetrahedra, OH groups, and H{sub 2}O groups. The structural unit of ThS1 is an isolated cluster consisting of a single Th polyhedron with two monodentate SO{sub 4} tetrahedra and seven H{sub 2}O groups. A double-wide Th sulfate chain is the basis of ThS2. The structures of ThS3 and ThS4 are frameworks of Th polyhedra and sulfate tetrahedra, and each contains channels that extend through the framework. One of the Th cations in ThS3 is coordinated by a bidentate SO{sub 4} tetrahedron, and ThS4 is unusual in the presence of a pair of Th cations that share a polyhedral face. - Graphical abstract: The structures of four hydrous thorium sulfates are reported that have structural units consisting of finite clusters, chains, and frameworks. Highlights: > Four hydrous thorium sulfates have structural units consisting of finite clusters, chains, and frameworks. > In each the Th cations are coordinated by nine O atoms from SO{sub 4} tetrahedra, OH groups, and H{sub 2}O groups. > The details of the linkages of ThO{sub 9} polyhedra and sulfate tetrahedra vary considerably in these structures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗