Three-dimensional framework of uranium-centered polyhedra with non-intersecting channels in the uranyl oxy-vanadates A{sub 2}(UO{sub 2}){sub 3}(VO{sub 4}){sub 2}O (A=Li, Na)
- Unite de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d'Ascq Cedex (France)
The uranyl vanadates A{sub 2}(UO{sub 2}){sub 3}(VO{sub 4}){sub 2}O (A=Li, Na) have been synthesized by solid-state reaction and the structure of the Li compound was solved from single-crystal X-ray diffraction. The crystal structure is built from {sub {infinity}}{sup 1}[UO{sub 5}]{sup 4{sup -}} chains of edge-shared U(2)O{sub 7} pentagonal bipyramids alternatively parallel to a-vector- and b-vector-axis and further connected together to form a three-dimensional (3-D) arrangement. The perpendicular chains are hung on both sides of a sheet {sub {infinity}}{sup 2}[(UO{sub 2})(VO{sub 4}){sub 2}]{sup 4-} parallel to (001), formed by U(1)O{sub 6} square bipyramids connected by VO{sub 4} tetrahedra, and derived from the autunite-type sheet. The resulting 3-D framework creates non-intersecting channels running down the a-vector- and b-vector-axis formed by empty face-shared oxygen octahedra, the Li{sup +} ions are displaced from the center of the channels and occupy the middle of one edge of the common face. The peculiar position of the Li{sup +} ion together with the full occupancy explain the low conductivity of Li{sub 2}(UO{sub 2}){sub 3}(VO{sub 4}){sub 2}O compared with that of Na(UO{sub 2}){sub 4}(VO{sub 4}){sub 3} containing the same type of channels half occupied by Na{sup +} ions in the octahedral sites. Crystallographic data for Li{sub 2}(UO{sub 2}){sub 3}(VO{sub 4}){sub 2}O: tetragonal, space group I41/amd, a=7.3303(5)A, c=24.653(3)A, V=1324.7(2)A{sup 3}, Z=4, {rho}{sub mes}=5.32(2)g/cm{sup 3}, {rho}{sub cal}=5.36(3)g/cm{sup 3}, full-matrix least-squares refinement basis on F{sup 2} yielded, R{sub 1}=0.032, wR{sub 2}=0.085 for 37 refined parameters with 364 independent reflections with I>=2{sigma}(I)
- OSTI ID:
- 21015723
- Journal Information:
- Journal of Solid State Chemistry, Vol. 180, Issue 3; Other Information: DOI: 10.1016/j.jssc.2006.12.014; PII: S0022-4596(06)00647-5; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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