Podrobnosti záznamu

Název
    The crystal structure and crystal chemistry of uranosphaerite, Bi(UO2)O2OH
Údaj o odpovědnosti
    Karrie-Ann Hughes, Peter C. Burns, Uwe Kolitsch
Autor
    Burns, Peter C.
    Hughes, Karrie-Ann
    Kolitsch, Uwe
Jazyk
    anglicky
Zdrojový dokument - seriál
    Canadian mineralogist
Svazek/č.
    Vol. 41, no. 3
Strany
    p. 677-685
Rok
    2003
Poznámky
    5 obr., 4 tab., 2 s. bibl.
    Francouzské resumé
    il.
    Zkr. název ser.: Canad. Mineralogist
Předmětová skupina
    bizmut
    krystalochemie
    krystalová struktura
    minerály uranu
    oxidy
    syntéza minerálu
    uran
Geografické jméno
    ČR-Čechy
    Měděnec (Chomutov)
    SRN-Baden-Württemberg
Klíčové slovo
    Bi(UO2)O2OH
    Chemistry
    Crystal
    Structure
    Uranosphaerite
Abstrakt (anglicky)
   he crystal structure of uranosphaerite, Bi(UO2)O2OH, has been solved and refined using single-crystal X-ray-diffraction data collected from synthetic and natural crystals. The structure of natural uranosphaerite from the Clara barite and fluorite mine, Black Forest, Germany, was refined to an agreement index (R1) of 2.86 per cent, calculated for 1194 unique observed reflections (|F0|4sigmaF). Uranosphaerite is monoclinic, space group P21/n, a 7.559(2), b 7.811(2), c 7.693(2) angstrom, beta 92.88(3)°, V 453.6(2) angstrom3. Crystals of synthetic uranosphaerite were obtained by mild hydrothermal techniques; the structure was refined to an R1 of 5.84 per cent calculated for 1590 unique observed reflections (|F0| > 4sigmaF). The synthetic crystal has slightly smaller unit-cell dimensions, a 7,540(3), b 7.801 (3), c 7.674(3) angstrom, beta 92.948(7)°, V 450.75( 1) angstrom3.
   The structure consists of one symmetrically distinct U6+ cation that is bonded to two atoms of oxygen, forming a nearly linear uranyl ion [(UO2)2+, designated Ur]. The uranyl ion is further coordinated by five O and OH anions, resulting in a pentagonal bipyramid capped by the oxygen atoms of the uranyl ion. The single symmetrically distinct Bi3+ cation in the structure is coordinated by four anions arranged at the base of a pyramid that is capped by Bi3+, consistent with the presence of a lone pair of electrons on Bi3+. The Bi3+ cation is weakly bonded to two additional OUr atoms. Urfí5(fí: O, OH) pentagonal bipyramids share an equatorial edge, giving a dimer. Pairs of Bifí4 polyhedra also share an edge, and the resulting dimers are linked to the dimers of uranyl polyhedra, forming a heteropolyhedral sheet that is parallel to(101). Adjacent sheets are linked by weak Bi-O bonds and by weak hydrogen bonds. The sheet is based upon the anion-topology of the francevillite sheet
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    26. 9. 2007
Datum importu
    8. 8. 2012