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Title
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The crystal structure of Na-2(UO2)(2)SiO4F2, a compound structurally related to soddyite, and formed during uranyl silicate synthesis in Teflon-lined bombs
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Author
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Abstract
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| During the formation of sodium-boltwoodite from boltwoodite in a Teflon(R) vessel, a new uranyl compound with composition Na-2(UO2)(2)SiO4F2 was formed. The yellow crystals have tetragonal structure, a 6.975(8)Angstrom, c = 18.31(2) Angstrom, V = 891(2) Angstrom(3), D-c = 5.348 g cm(-3), Z = 4, space group I4(1)/amd(No 141). The crystal structure was solved by Patterson methods and refined to an unweighted residual of 0.030, based on 204 observed (F-2 > 4 sigma F-2) reflections measured with MoK alpha X-radiation on a single-crystal diffractometer. The structure is build up of UO6F pentagonal bipyramids which form endless chains by edge sharing. The chains are joined by sharing edges with SiO4 tetrahedra, resulting in a framework structure. Sodium atoms are surrounded by two fluorine and four oxygen atoms. The strongest ten reflections of the X-ray powder pattern [d(Angstrom), (I), hkl] are: 4.599(100)013, 3.492(89)200, 2.599(84)116, 6.53(75)011, 4.348(67)112, 1.791(63) 316, 3.247(59)105, 2.781(57)123, 3.078(37)121 and 1.957(34)109. The infrared spectrum was recorded. |
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Language
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English
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Source (journal)
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Neues Jahrbuch für Mineralogie: Monatshefte. - Stuttgart
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Publication
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Stuttgart
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1999
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ISSN
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0028-3649
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Volume/pages
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6
(1999)
, p. 253-264
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ISI
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000081356900002
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