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The structures of becquerelite and Sr-exchanged becquerelite

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Published/Copyright: March 28, 2015
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American Mineralogist
From the journal American Mineralogist Volume 87 Issue 4

Abstract

The crystal structures of becquerelite, Ca[(UO2)6O4(OH)6](H2O)8, and Sr-exchanged becquerelite obtained by ion exchange, Sr1.27[(UO2)3O3.54(OH)1.46](H2O)3, have been refined using diffraction data collected with MoKa X-rays and a CCD-based detector. The structure of becquerelite, orthorhombic, space group Pn21a, a = 13.8527(5), b = 12.3929(4), c = 14.9297(5) Å, V = 2563.2(1) Å3, has been refined on the basis of F2 for 4875 unique reflections to R1 = 3.39%, calculated using 4581 unique observed reflections (|F| ≥ 4σF), and a goodness-of-fit (S) of 1.04. Sr-exchanged becquerelite was obtained by placing single crystals of synthetic becquerelite in 2.5 M SrCl2 solution for 60 h at 160 °C. The structure of Sr-exchanged becquerelite is trigonal, space group P3, a = 7.020(4), c = 6.992(6) Å, V = 298.4(3) Å3, and has been refined on the basis of F2 for 683 unique reflections to R1 = 4.26%, calculated using the 564 unique observed reflections (|F| ≥ 4σF), and an S of 1.01. The results for becquerelite confirm the cation polyhedra and structural connectivity reported previously, but collection of data for a high-quality crystal using a CCD-based detector has substantially improved the precision of the atom positions. The structure contains a-U3O8-type sheets of uranyl pentagonal bipyramids, with a single symmetrically distinct Ca cation and eight symmetrically distinct H2O groups located in the interlayer. The structure of Sr-exchanged becquerelite also contains α-U3O8-type sheets of uranyl pentagonal bipyramids, although the amount of H in the sheets is lower than for becquerelite. The interlayer contains two symmetrically distinct Sr cations and a single H2O group. Ion exchange of Sr into the interlayer of becquerelite without destruction of the crystals has potential important implications for the mobility of 90Sr in contaminated areas, and for the geologic disposal of nuclear waste.

Received: 2000-9-27
Accepted: 2002-1-9
Published Online: 2015-3-28
Published in Print: 2002-4-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. Titanium in biotite from metapelitic rocks: Temperature effects, crystal-chemical controls, and petrologic applications
  2. Local equilibrium in polymetamorphic gneiss and the titanium substitution in biotite
  3. The enthalpy of formation and internally consistent thermodynamic data of Mg-staurolite
  4. Coexisting andalusite, kyanite, and sillimanite: Sequential formation of three Al2SiO5 polymorphs during progressive metamorphism near the triple point, Sivrihisar, Turkey
  5. Co-existing aluminum silicates in quartz veins: A quantitative approach for determining andalusite-sillimanite equilibrium in natural samples using oxygen isotopes
  6. Stability of corundum + quartz relative to kyanite and sillimanite at high temperature and pressure
  7. Andalusite-sillimanite replacement (Mazarrón, SE Spain): A microstructural and TEM study
  8. Hydroxyl-rich topaz in high-pressure and ultrahigh-pressure kyanite quartzites, with retrograde woodhouseite, from the Sulu terrane, eastern China
  9. Coesite exsolution from supersilicic titanite in UHP marble from the Kokchetav Massif, northern Kazakhstan
  10. Composition of synthetic tremolite-tschermakite solid solutions in amphibole + anorthiteand amphibole + zoisite-bearing assemblages
  11. Paragenesis and thermobarometry of Ca-amphiboles in the Barcroft granodioritic pluton, central White Mountains, eastern California
  12. B and Li in Proterozoic metapelites from the Black Hills, U.S.A.: Implications for the origin of leucogranitic magmas
  13. The role of Fe and cation order in the crystal chemistry of surinamite, (Mg,Fe2+)3(Al,Fe3+)3O[AlBeSi3O15]: A crystal structure, Mössbauer spectroscopic, and optical spectroscopic study
  14. Fe3+ and Fe2+ partitioning among silicates in metapelites: A synchrotron micro-XANES study
  15. Thermodynamic and structural behavior of analcime–leucite analogue systems
  16. In-situ synchrotron study of the kinetics, thermodynamics, and reaction mechanisms of the hydrothermal crystallization of gyrolite, Ca16Si24O60(OH)8·14H2O
  17. The crystal structures of grossular and spessartine between 100 and 600 K and the crystal chemistry of grossular-spessartine solid solutions
  18. The structures of becquerelite and Sr-exchanged becquerelite
  19. Elasticity and equation of state of orthoenstatite, MgSiO3
  20. Reidite: An impact-produced high-pressure polymorph of zircon found in marine sediments
  21. A new polymorph of eucryptite (LiAlSiO4), ε-eucryptite, and thermal expansion of α- and ε-eucryptite at high pressure
  22. Disordering during melting: An 17O NMR Study of crystalline and glassy CaTiSiO5 (titanite)
  23. Characterization of Mn oxides in cemented streambed crusts from Pinal Creek, Arizona, U.S.A., and in hot-spring deposits from Yuno-Taki Falls, Hokkaido, Japan
https://doi.org/10.2138/am-2002-0418

Articles in the same Issue

  1. Titanium in biotite from metapelitic rocks: Temperature effects, crystal-chemical controls, and petrologic applications
  2. Local equilibrium in polymetamorphic gneiss and the titanium substitution in biotite
  3. The enthalpy of formation and internally consistent thermodynamic data of Mg-staurolite
  4. Coexisting andalusite, kyanite, and sillimanite: Sequential formation of three Al2SiO5 polymorphs during progressive metamorphism near the triple point, Sivrihisar, Turkey
  5. Co-existing aluminum silicates in quartz veins: A quantitative approach for determining andalusite-sillimanite equilibrium in natural samples using oxygen isotopes
  6. Stability of corundum + quartz relative to kyanite and sillimanite at high temperature and pressure
  7. Andalusite-sillimanite replacement (Mazarrón, SE Spain): A microstructural and TEM study
  8. Hydroxyl-rich topaz in high-pressure and ultrahigh-pressure kyanite quartzites, with retrograde woodhouseite, from the Sulu terrane, eastern China
  9. Coesite exsolution from supersilicic titanite in UHP marble from the Kokchetav Massif, northern Kazakhstan
  10. Composition of synthetic tremolite-tschermakite solid solutions in amphibole + anorthiteand amphibole + zoisite-bearing assemblages
  11. Paragenesis and thermobarometry of Ca-amphiboles in the Barcroft granodioritic pluton, central White Mountains, eastern California
  12. B and Li in Proterozoic metapelites from the Black Hills, U.S.A.: Implications for the origin of leucogranitic magmas
  13. The role of Fe and cation order in the crystal chemistry of surinamite, (Mg,Fe2+)3(Al,Fe3+)3O[AlBeSi3O15]: A crystal structure, Mössbauer spectroscopic, and optical spectroscopic study
  14. Fe3+ and Fe2+ partitioning among silicates in metapelites: A synchrotron micro-XANES study
  15. Thermodynamic and structural behavior of analcime–leucite analogue systems
  16. In-situ synchrotron study of the kinetics, thermodynamics, and reaction mechanisms of the hydrothermal crystallization of gyrolite, Ca16Si24O60(OH)8·14H2O
  17. The crystal structures of grossular and spessartine between 100 and 600 K and the crystal chemistry of grossular-spessartine solid solutions
  18. The structures of becquerelite and Sr-exchanged becquerelite
  19. Elasticity and equation of state of orthoenstatite, MgSiO3
  20. Reidite: An impact-produced high-pressure polymorph of zircon found in marine sediments
  21. A new polymorph of eucryptite (LiAlSiO4), ε-eucryptite, and thermal expansion of α- and ε-eucryptite at high pressure
  22. Disordering during melting: An 17O NMR Study of crystalline and glassy CaTiSiO5 (titanite)
  23. Characterization of Mn oxides in cemented streambed crusts from Pinal Creek, Arizona, U.S.A., and in hot-spring deposits from Yuno-Taki Falls, Hokkaido, Japan
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