Channels occupancy and distortion in new lithium uranyl phosphates with three-dimensional open-frameworks

Journal Article · Mon Jun 15 00:00:00 EDT 2009 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2009.02.024· OSTI ID:21370424

Renard, C ^[1]; Obbade, S; Abraham, F ^[1]

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1. Unite de Catalyse et de Chimie du Solide (CNRS UMR 8181), ENSC Lille-UST Lille, BP 90108, 59652 Villeneuve d'Ascq cedex (France)

Three new lithium uranyl phosphates, Li{sub 2}(UO{sub 2}){sub 3}(PO{sub 4}){sub 2}O (1), Li(UO{sub 2}){sub 4}(PO{sub 4}){sub 3} (2) and Li{sub 3}(UO{sub 2}){sub 7}(PO{sub 4}){sub 5}O (3) were synthesized and studied. Powders of 1 and 2 were synthesized via solid state reaction, and single crystals of the three compounds were obtained by melting of 1 and 2 powders. The structures of the three compounds have been solved and refined from single crystal X-ray diffraction data. In the three compounds, the uranium atoms occupy square and pentagonal bipyramids. The uranium square bipyramids and phosphate tetrahedra are connected by vertices to form two types of layers with autunite sheet anion-topology {sub i}nfinity{sup 2}[(UO{sub 2})(PO{sub 4}){sub 2}]{sup 4-} and {sub i}nfinity{sup 2}[(UO{sub 2}){sub 2}(PO{sub 4}){sub 3}]{sup 5-}denoted S and D, respectively. The uranyl pentagonal bipyramids share opposite equatorial edges to form {sub i}nfinity{sup 1}[UO{sub 5}]{sup 4-} infinite chains. Mutually perpendicular chains are hung on each side of the sheets to build frameworks with non-crossing perpendicular channels that accommodate the lithium ions. Various stacking sequences of the S and D layers, S-S, D-D and S-D, generate three different frameworks in 1, 2 and 3, respectively. These compounds are similar to the recently reported vanadate analogous. However, the phosphate tetrahedra, smaller than the vanadate ones, gives distortion of the layers and a lowering of the symmetry and/or a change of periodicity. The electrical conductivity of 1 and 2 was measured using impedance spectroscopy method. The rather low conductivity of the lithium cations is explained by the crystal structure and the Li{sup +} position within the tunnels. These results corroborate those on the analogous three-dimensional alkaline uranyl vanadates. Crystallographic data: 293 K, BRUKER X8-APEX2 X-ray diffractometer, 4 K CCD detector, MoKalpha, lambda=0.71073 A, full-matrix least-squares refinement on the basis of F. 1, Tetragonal symmetry, space group I4{sub 1}/amd, Z=4 with a=7.1109(2) A and c=25.0407(8) A, R=0.034 and wR=0.047 for 38 parameters with 479 independent reflections with I>=3sigma(I). 2, monoclinic symmetry, space group P2{sub 1}/c, Z=4 and a=9.8829(2) A, b=9.8909(2) A, c=17.4871(4) A and beta=106.198(1){sup o}, R=0.021 and wR=0.031 for 249 parameters with 4201 independent reflections with I>=3sigma(I). 3, Tetragonal symmetry, space group P4-bar2{sub 1}m with a=9.9305(2) A and c=14.5741(3) A, R=0.035 and wR=0.038 for 137 parameters with 4527 independent reflections with i>=3sigma(I). - Graphical abstract: The three new lithium uranyl phosphates Li{sub 2}(UO{sub 2}){sub 3}(PO{sub 4}){sub 2}O, Li(UO{sub 2}){sub 4}(PO{sub 4}){sub 3} and Li{sub 3}(UO{sub 2}){sub 7}(PO{sub 4}){sub 5}O were synthesised via solid state reaction. The structures of these compounds are based upon three-dimensional open-frameworks built from {sub i}nfinity{sup 1}[UO{sub 5}]{sup 4-} chains connected through two types of layers, S and D, in the sequences S-S, D-D and S-D, respectively. The lithium atoms distribution along the channels induces various distortions of the {sub i}nfinity{sup 1}[UO{sub 5}]{sup 4-} chains.

• OSTI ID: 21370424
• Journal Information: Journal of Solid State Chemistry, Vol. 182, Issue 6; Other Information: DOI: 10.1016/j.jssc.2009.02.024; PII: S0022-4596(09)00083-8; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AUTUNITE
CRYSTALLOGRAPHY
ELECTRIC CONDUCTIVITY
IMPEDANCE
LEAST SQUARE FIT
LITHIUM COMPOUNDS
LITHIUM IONS
LITHIUM SULFIDES
MONOCLINIC LATTICES
MONOCRYSTALS
SHEETS
SPACE GROUPS
SPECTROSCOPY
TETRAGONAL LATTICES
URANYL PHOSPHATES
X-RAY DIFFRACTION
ACTINIDE COMPOUNDS
ALKALI METAL COMPOUNDS
CHALCOGENIDES
CHARGED PARTICLES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
DIFFRACTION
ELECTRICAL PROPERTIES
IONS
MATERIALS
MATHEMATICAL SOLUTIONS
MAXIMUM-LIKELIHOOD FIT
MINERALS
NUMERICAL SOLUTION
OXYGEN COMPOUNDS
PHOSPHATE MINERALS
PHOSPHATES
PHOSPHORUS COMPOUNDS
PHYSICAL PROPERTIES
RADIOACTIVE MATERIALS
RADIOACTIVE MINERALS
SCATTERING
SULFIDES
SULFUR COMPOUNDS
SYMMETRY GROUPS
URANIUM COMPOUNDS
URANIUM MINERALS
URANYL COMPOUNDS