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The structure of aperiodic, metamict (Ca, Th)ZrTi2O7 (zirconolite): An EXAFS study of the Zr, Th, and U sites

Published online by Cambridge University Press:  31 January 2011

François Farges ,
Rodney C. Ewing  and
Gordon E. Brown Jr.
François Farges
Affiliation:
Laboratoire des Géomatériaux, Institut de Physique du Globe de Paris (and Université Marne-la-Vallée), 4 place Jussieu, 75252 Paris Cedex 05, France, and Department of Geological & Environmental Sciences and Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, California 94305-2115
Rodney C. Ewing
Affiliation:
Department of Earth & Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131-1116
Gordon E. Brown Jr.
Affiliation:
Department of Geological & Environmental Sciences and Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, California 94305-2115
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Abstract

The structural environments of Zr, Th, and U in aperiodic (metamict) (Ca, Th)ZrTi2O7 were examined using Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. Samples are aperiodic due to a radiation-induced transformation caused by alpha-decay event damage. In the aperiodic samples, Zr is mainly 7-coordinated [d(Zr−O) ≍ 2.14–2.17 ≍ 0.02 Å]; whereas, Th is mainly 8-coordinated [d(Th–O) ≍ 2.40−2.41 ≍ 0.03 Å]. Nearly identical bond lengths and coordination numbers for these elements were determined for an annealed, crystalline sample. The radiation-induced transition from the periodic to the aperiodic state is characterized by a significant broadening of the distribution of (Zr, Th)–O distances. In one metamict sample with ≍1.9 wt.% U3O8, U is essentially tetravalent. The absence of higher oxidation states (U6+) is consistent with the lack of evidence for alteration (samples are over 500 million years old). The reduced medium-range order around Zr, Th, and U is related to the increase of alpha-decay event damage and precludes decomposition of zirconolite into simple oxides of Zr, Th, or U. Comparison with other metamict (Zr, Th, U)-bearing phases (e.g., ZrSiO4 and ThSiO4) suggests that Zr4+, Th4+, and U4+ prefer 7-, 8-, and 6-coordinated sites, respectively, in aperiodic phases at ambient temperatures and pressures. Examination of the structure of crystalline (Ca, Th)ZrTi2O7 demonstrates that M–O–M angles (M = Ca, Ti, Zr, and Th) are relatively small (≍100–120° for edge-sharing polyhedra). A limited relaxation of the constraints of periodicity around M cations caused by radiation damage (e.g., tilting of polyhedra) dramatically affects the distribution of these angles. This type of structural relaxation may be the mechanism by which long-range periodicity is lost and medium-range order is reduced with increasing radiation damage, while the major cations retain their nearest-neighbor environments. This relaxation may also help explain the lattice expansion observed in zirkelites when they undergo radiation damage.

Type
Articles
Information
Journal of Materials Research , Volume 8 , Issue 8 , August 1993 , pp. 1983 - 1995
Copyright
Copyright © Materials Research Society 1993

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References

REFERENCES

1Ringwood, A.E., Kesson, S.E., Ware, N. G., Hibberson, W., and Major, A., Nature 278, 219 (1979).CrossRefGoogle Scholar
2White, T. J., Segall, R. L., and Turner, P. S., Angew. Chem. 24, 357 (1985).CrossRefGoogle Scholar
3Kesson, S.E., Sinclair, W.J., and Ringwood, A.E., Nucl. Chem. Waste Management 4, 259 (1983).Google Scholar
4Ringwood, A.E., Kesson, S.E., Reeve, K.D., Levins, D.M., and Ramm, E. J., Radioactive Waste Forms for the Future, edited by Lutze, W. and Ewing, R. C. (North-Holland, Amsterdam, 1988), pp. 233–334.Google Scholar
5Ewing, R.C., Chakoumakos, B.C., Lumpkin, G.R., and Murakami, T., Mater. Res. Bull. XII, 58 (1987).CrossRefGoogle Scholar
6Ewing, R.C., Haaker, R.F., Headley, T.J., and Hlava, P.F., in Scientific Basis for Nuclear Waste Management, edited by Topp, S. V. (Elsevier, North Holland, New York, 1982), Vol. VI, p. 249.Google Scholar
7Ewing, R.C. and Headley, T.J., J. Nucl. Mater. 119, 102 (1983).CrossRefGoogle Scholar
8Lumpkin, G. R., Ewing, R. C., Chakoumakos, B. C., Greegor, R. B., Lytle, F. W., Foltyn, E. M., Clinard, F. W. Jr., Boatner, L. A., and Abraham, M. M., J. Mater. Res. 1, 564 (1986).CrossRefGoogle Scholar
9Lumpkin, G.R. and Ewing, R.C., Phys. Chem. Minerals 16, 2 (1988).CrossRefGoogle Scholar
10Rossell, H.J., Nature 283, 282 (1980).CrossRefGoogle Scholar
11Gatehouse, B.M., Grey, I.E., Roderick, J.H., and Rossell, H.J., Acta Crystallogr. B 37, 306 (1981).CrossRefGoogle Scholar
12Sinclair, W. and Eggleton, R.A., Am. Mineral. 67, 615 (1982).Google Scholar
13Mazzi, F. and Munno, R., Am. Mineral. 68, 262 (1983).Google Scholar
14Greegor, R.B., Lytle, F.W., Ewing, R.C., and Haaker, R.F., in EXAFS and Near-edge Structure III, edited by Hogdson, K., Hedman, B., and Penner-Hahn, J. E. (Springer-Verlag, New York, 1984), Vol. 2, p. 343.CrossRefGoogle Scholar
15Blake, G. S. and Smith, G. F., Mineral. Mag. 16, 309 (1913).Google Scholar
16Lytle, F.W., Greegor, R.B., Sandstrom, D.R., Marques, D.R., Wong, J., Spiro, C. L., Huffman, G.P., and Huggins, F.E., Nucl. Instrum. Methods 226, 542 (1984).CrossRefGoogle Scholar
17Bonin, D., Calas, G., Suquet, H., and Pezerat, H., Phys. Chem. Minerals 12, 55 (1985).CrossRefGoogle Scholar
18Sayers, D. E., Lytle, F. W., and Stern, E. A., Phys. Rev. Lett. 27, 1204 (1971); E.A. Stern, Phys. Rev. B 10, 3027 (1974); B.K. Teo, P. A. Lee, A. L. Simons, P. Eisenberger, and B. M. Kincaid, J. Am. Chem. Soc. 99, 3854 (1977); P. A. Lee, P.H. Citrin, P. Eisenberger, and B.M. Kincaid, Rev. Mod. Phys. 53, 769 (1981).CrossRefGoogle Scholar
19Foex, M., Traverse, J-P., and Coutures, J., C.R. Acad. Sci. Paris Ser. C 264, 1837 (1967).Google Scholar
20Teo, B.K. and Lee, P.A., J. Am. Chem. Soc. 101, 2815 (1979); A.G. McKale, B.W. Veal, A. P. Paulikas, S.K. Chan, and G.S. Knapp, J. Am. Chem. Soc. 110, 3763 (1988).CrossRefGoogle Scholar
21Wyckoff, R.W.G., Crystal Structures, 2nd ed. (John Wiley & Sons, New York, 1963), Vol. I, p. 467.Google Scholar
22Eisenberger, P. and Brown, G. S., Solid State Commun. 29, 481 (1979).CrossRefGoogle Scholar
23Smith, D. K. and Newkirk, H. W., Acta Crystallogr. 18, 983 (1967).CrossRefGoogle Scholar
24Taylor, M. and Ewing, R. C., Acta Crystallogr. B 34, 1074 (1978).CrossRefGoogle Scholar
25Farges, F., Ponader, C.W., and Brown, G.E. Jr., Geochim. Cos-mochim. Acta 55, 1563 (1991).CrossRefGoogle Scholar
26Farges, F., Geochim. Cosmochim. Acta 55, 3303 (1991).CrossRefGoogle Scholar
27Teo, B. K., in EXAFS: Basic Principles and Data Analysis, Inorganic Chemistry Concepts (Springer-Verlag, New York, 1986), Vol. IX, p. 349.CrossRefGoogle Scholar
28Farges, F. and Calas, G., Am. Mineral. 76, 60 (1991).Google Scholar
29Farges, F., Ponader, C.W., Calas, G., and Brown, G.E. Jr., Geochim. Cosmochim. Acta 56, 4205 (1992).CrossRefGoogle Scholar
30Petit-Maire, D., Petiau, J., Calas, G., and Jacquet-Francillon, N., J. Phys. 47, C8, 849 (1986).Google Scholar
31Vance, E.R. and Anderson, B.W., Mineral. Mag. 38, 605 (1972).CrossRefGoogle Scholar
32Greegor, R. B., Lytle, F. W., Chakoumakos, B. C., Lumpkin, G. R., and Ewing, R. C., in Scientific Basis for Nuclear Waste Managment IX, edited by Werme, L. O. (Mater. Res. Soc. Symp. Proc. 50, Pittsburgh, PA, 1986), p. 387.Google Scholar
33Cotton, F. A. and Wilkinson, G., in Advanced Inorganic Chemistry, 5th ed. (Wiley International, New York, 1988), 1455 pp.Google Scholar
34Farges, F., Ph.D. Thesis (Universite Paris 7, 1989), 162 pp.Google Scholar
35For a review, see Veal, B.W., Mundy, J.N., and Lam, D.J., in Handbook on the Physics and Chemistry of the Actinides, edited by Freeman, A. J. and Lander, G. H. (Elsevier, Amsterdam, 1987), p. 271.Google Scholar
36Pauling, L., J. Am. Chem. Soc. 51, 1010 (1928).CrossRefGoogle Scholar
37Brown, I. D. and Altermatt, D., Acta Crystallogr. B 41, 244 (1985); N.E. Brese and M. O'Keefe, Acta Crystallogr. B 47, 192 (1991).CrossRefGoogle Scholar
38Weber, W.J., J. Mater. Res. 5, 2687 (1990).CrossRefGoogle Scholar
39Wald, J. W. and Offerman, P., in Scientific Basis for Nuclear Waste Management, edited by Lutze, W. (Elsevier-North Holland, New York, 1982), Vol. V, p. 369; F.W. Clinard, Jr., Ceram. Bull. 65, 1181 (1986).Google Scholar
40Ilyushin, G. D., Voronkov, A. A., Ilyukhin, V. V., Nevskii, N. N., and Belov, N.V., Sov. Phys. Dokl. 26, 808 (1981).Google Scholar
41Cannillo, E., Rossi, G., and Ungaretti, L., Am. Mineral. 58, 106 (1973).Google Scholar
42Munno, R., Rossi, G., and Tadini, C., Am. Mineral. 65, 188 (1980).Google Scholar
43Smith, D. K. and Newkirk, H. W., Acta Crystallogr. 18, 983 (1965).CrossRefGoogle Scholar
44Hazen, R.M. and Finger, L.W., Am. Mineral. 64, 157 (1979).Google Scholar
45Taylor, J.C., Zalkin, A., and Templeton, D.H., Acta Crystallogr. 20, 842 (1966); T. Ueki, A. Zalkin, and D.H. Templeton, Acta Crystallogr. 20, 836 (1966).CrossRefGoogle Scholar