Hostname: page-component-76fb5796d-22dnz Total loading time: 0 Render date: 2024-04-26T13:44:43.824Z Has data issue: false hasContentIssue false
  • English
  • Français

Distinguishing among schoepite, [(UO2)8O2(OH)12](H2O)12, and related minerals by X-ray powder diffraction

Published online by Cambridge University Press:  10 January 2013

Robert J. Finch ,
Frank C. Hawthorne ,
Mark L. Miller  and
Rodney C. Ewing
Robert J. Finch
Affiliation:
Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada
Frank C. Hawthorne
Affiliation:
Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada
Mark L. Miller
Affiliation:
Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, 87131
Rodney C. Ewing
Affiliation:
Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, 87131
Get access Rights & Permissions [Opens in a new window]

Abstract

We have calculated X-ray powder-diffraction data for schoepite, [(UO2)8O2(OH)12](H2O)12, using unit-cell and atomic parameters from the crystal structure (a 14.337, b 16.813, c 14.781, Z=4, Dx=4.87 gcm−3). Schoepite crystallizes in space group P21ca but is strongly pseudo- centrosymmetric, and observed reflections (Irel>0.1%) conform to space group Pbca. The six strongest reflections for schoepite are [d(Å), hkl (relative intensity)] 7.365, 002 (100), 3.253, 242 (55), 3.626, 240 (36), 3.223, 402 (25), 3.683, 004 (20), 2.584, 244 (18). The calculated intensities of reflections that distinguish space group Pbca from space group Pbna (the space group of metaschoepite), i.e., h0l with h odd and l even, are weak, and may not be evident in experimental powder patterns. The a axis of schoepite (14.34 Å) is significantly longer than that of synthetic metaschoepite (13.98 Å), and the two phases can best be distinguished by their unit-cell parameters. However, potential overlap of the strongest reflections can make identification and unit-cell determination difficult, especially for fine-grained material. Natural samples commonly contain intergrowths of schoepite, metaschoepite, and dehydrated schoepite. The calculated powder pattern for schoepite agrees well with data reported for natural schoepite (PDF 13-241) but shows discrepancies with the data from synthesis products. Data for “synthetic schoepite” indicate that this product was a mixture. Powder data labeled “paraschoepite” in the Powder Diffraction File do not correspond to the mineral of that name.

Type
Research Article
Information
Powder Diffraction , Volume 12 , Issue 4 , December 1997 , pp. 230 - 238
Copyright
Copyright © Cambridge University Press 1997

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Burns, P. C., Finch, R. J., Hawthorne, F. C., Miller, M. L., and Ewing, R. C. (1997). “The crystal structure of ianthinite, [U 4+2(UO 2)4O 6(OH)4(H 2O)4](H 2O)5, a possible phase for Pu 4+ incorporation during oxidation of spent nuclear fuel,” J. Nucl. Mater. (in press).Google Scholar
Burns, P. C., Miller, M. L., and Ewing, R. C. (1996). “U 6+ minerals and inorganic phases: A comparison and hierarchy of crystal structures,” Can. Mineral. 34, 845–880.Google Scholar
Bruno, J., and Sandino, A. (1989). “The solubility of amorphous and crystalline schoepite in neutral to alkaline aqueous solutions,” inScientific Basis for Nuclear Waste Management XII, edited by W. Lutze and R. C. Ewing [Mater. Res. Soc. Symp. Proc. 127, 871–878].CrossRefGoogle Scholar
Čejka, J., Sejoora, J., and Deliens, M. (1996). “New data on studtite, UO 4·4H 2O, from Shinkolobwe, Shaba, Zaire,” Neues Jahrb. Mineral. Mh. H3, 125–134.Google Scholar
Christ, C. L., and Clark, J. R. (1960). “Crystal chemical studies of some uranyl oxide hydrates,” Am. Mineral. 45, 1026–1061.Google Scholar
Christ, C. L. (1965). “Phase transformations and crystal chemistry of schoepite,” Am. Mineral. 50, 235–239.Google Scholar
Cordfunke, E. H. P., Prins, G., and Van Vlaanderen, P. (1968). “Preparation and properties of the violet ‘U 3O 8 hydrate,’”J. Inorg. Nucl. Chem. 30, 1745–1750.CrossRefGoogle Scholar
Cordfunke, E. H. P. (1962). “On the uranates of ammonium-I. The ternary system NH 3–UO 3–H 2O,”J. Inorg. Nucl. Chem. 24, 303–307.CrossRefGoogle Scholar
Cromer, D. T., and Liberman, D. (1970). “Relativistic calculations of anomalous scattering factors,” J. Chem. Phys. 53, 1891–1898.CrossRefGoogle Scholar
Cromer, D. T., and Mann, J. B. (1968). “X-ray scattering factors computed from numerical Hartree–Fock wave functions,” Acta Crystallogr. A24, 321–324.CrossRefGoogle Scholar
Cullity, B. D. (1981). Elements of X-ray Diffraction (Addison-Wesley, Reading, Mass.), p. 555.Google Scholar
Debets, P. C., and Loopstra, B. O. (1963). “On the uranates of ammonium-II. X-ray investigations in the system NH 3–UO 3–H 2O,”J. Inorg. Nucl. Chem. 25, 945–953.CrossRefGoogle Scholar
Deliens, M. (1977).Associations de minéraux secondaires d’uranium à Shinkolobwe (région du Shaba, Zaïre),” Bull. Soc. Fr. Minéral. Cristallogr. 100, 32–38.Google Scholar
Deliens, M., and Piret, P. (1983). “Metastudtite, UO 4·H 2O a new mineral from Shinkolobwe, Shaba, Zaire,” Am. Mineral. 68, 456–458.Google Scholar
Evans, H. T. (1963). “Uranyl ion coordination,” Science 141, 154–158.CrossRefGoogle ScholarPubMed
Finch, R. J., Cooper, M. A., Hawthorne, F. C., and Ewing, R. C. (1996a). “The crystal structure of schoepite, [(UO 2)8O 2(OH)12](H 2O)12,” Can. Mineral. 34, 1071–1088.Google Scholar
Finch, R. J., Hawthorne, F. C., and Ewing, R. C. (1996b). “Schoepite and dehydrated schoepite,” inScientific Basis for Nuclear Waste Management XIX, Murphy, W. M., and Knecht, D. A., eds. [ Mater. Res. Soc. Symp. Proc. 412, 361–368].Google Scholar
Finch, R. J., and Ewing, R. C. (1992). “The corrosion of uraninite under oxidizing conditions,” J. Nucl. Mater. 190, 133–156.CrossRefGoogle Scholar
Finch, R. J., Miller, M. L., and Ewing, R. C. (1992). “Weathering of natural uranyl oxide hydrates: schoepite polytypes and dehydration effects,” Radiochim. Acta 58/59, 433–443.CrossRefGoogle Scholar
Finch, R. J., and Ewing, R. C. (1991). “Uraninite alteration in an oxidizing environment and its relevance to the disposal of spent nuclear fuel,” SKB Technical Report No. 91–15 (Swedish Nuclear Fuel and Waste Management Co., Stockholm), p. 114.Google Scholar
Forsyth, R., and Werme, L. O. (1992). “Spent fuel corrosion and dissolution,” J. Nucl. Mater. 190, 3–19.CrossRefGoogle Scholar
Frondel, C. (1958). Systematic Mineralogy of Uranium and Thorium. U. S. Geol. Surv. Bulletin No. 1064, 400.Google Scholar
Guillemin, C., and Protas, J. (1959). “Ianthinite et wyartite,” Bull. Soc. Fr. Minéral. Cristallogr. 82, 80–86.Google Scholar
Hoekstra, H. R., and Siegel, S. (1973). “The uranium trioxide–water system,” J. Inorg. Nucl. Chem. 35, 761–779.CrossRefGoogle Scholar
International Tables for X-ray Crystallography (1969). (Kynoch, Birmingham, England, p. 558).Google Scholar
Miller, M. L., Finch, R. J., Burns, P. C., and Ewing, R. C. (1996). “Description and classification of uranium oxide hydrate sheet anion topologies,” J. Mater. Res. 11, 3048–3056.CrossRefGoogle Scholar
Nickel, E. H., and Nichols, M. C. (1992). Mineral Reference Manual (Van Norstrand Reinhold, New York, p. 250).Google Scholar
Pearcy, E. C., Prikryl, J. D., Murphy, W. M., and Leslie, B. W. (1994). “Alteration of uraninite from the Nopal I deposit, Pen˜a Blanca District, Chihuahua, Mexico, compared to degradation of spent nuclear fuel in the proposed U.S. high-level nuclear waste repository at Yucca Mountain, Nevada,” Appl. Geochem. 9, 713–732.CrossRefGoogle Scholar
Peters, J.-M. (1967). “Synthesis et étude radiocristallographique d’uranates synthétiques du type oxyde double d’uranyle,” Mem. Soc. R. Sci. Liège, ser. 5, vol. 14, fasc. 3, 6–59.Google Scholar
Schoep, A., and Stradiot, S. (1947). “Paraschoepite and epiianthinite, two new uranium minerals from Shinkolobwe (Belgian Congo),” Am. Mineral. 32, 344–350.Google Scholar
Smith, D. K. (1989). POWD, a computer program for calculating X-ray powder diffraction patterns. VAX version 12.7—5 June, 1989. Department of Geosciences, The Pennsylvania State University.Google Scholar
Walker, T. L. (1923). “Schoepite, a new uranium mineral from Kasolo, Belgian Congo,” Am. Mineral 8, 67–69.Google Scholar
Walenta, K. (1974). “On studtite and its composition,” Am. Mineral. 59, 166–171.Google Scholar
Wronkiewicz, D. J., Bates, J. K., Wolf, S. F., and Buck, E. C. (1996). “Ten-year results from unsaturated drip tests with UO 2 at 90 °C: Implications for the corrosion of spent nuclear fuel,” J. Nucl. Mater. 238, 78–95.CrossRefGoogle Scholar
Wronkiewicz, D. J., Bates, J. K., Gerding, T. J., Veleckis, E.and Tani, B. S. (1992). “Uranium release and secondary phase formation during unsaturated testing of UO 2 at 90 °C,” J. Nucl. Mater. 190, 107–127.CrossRefGoogle Scholar