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Structural Effect of Pu Substitutions on the Zr-Site in Zirconolite

  • B.D. Begg (a1), R.A. Day (a1) and A. Brownscombe (a1)

Abstract

As the level of Pu4+ substituted on the Zr-site in CaZr1-xPuxTi2O7 zirconolite increased, from x=0.1 to 0.6, a series of structural transitions occurred from zirconolite-2M to zirconolite-4M and subsequently from zirconolite-4M to pyrochlore. The solid-solution limit for Pu4+ substituted on the Zr-site in zirconolite-2M was ~ 0.15 formula units. Zirconolite-4M was only stable over a narrow compositional range, centered about CaZr0.59Pu0.41Ti2O7, whilst the pyrochlore structure was stabilized with CaZr0.4Pu0.6Ti2O7 stoichiometry. The stability of the zirconolite polytypes is therefore sensitive to the average effective ionic size of the ions occupying the seven-coordinated Zr-site. The reduction in Pu from Pu4+ to Pu3+ destabilized the zirconolite-4M, producing a mixture of perovskite and possibly zirconolite-3T. The CaZr0.4Pu0.6Ti2O7 pyrochlore was also predominantly transformed to perovskite as a result of this reduction of Pu.

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1. Myers, B.R., Armantrout, G.A., Jantzen, C.M., Jostsons, A., McKibben, J.M., Shaw, H.F., Strachan, D.M. and Vienna, J.D., Technical Evaluation Panel Summary Report, Plutonium Immobilization Project, Report No. UCRL-ID-129315, 1998.
2. Ringwood, A.E., Kesson, S.E., Reeve, K.D., Levins, D.M. and Ramm, E.J., in: Lutze, W. and Ewing, R.C. (Eds.), Radioactive Waste Forms for the Future, North-Holland, Amsterdam, 1988, p. 233
3. Lumpkin, G.R., Hart, K.P., McGlinn, P.J., Payne, T.E., RGiere, . and Williams, C.T., Radiochim. Acta 66/67 469–74 (1994)
4. Rossell, H.J., Nature, 283, 282–83 (1980)
5. Gatehouse, B.M., Grey, I.E., Hill, R.J. and Rossell, H.J., Acta Cryst. Sect. B7, 306 ((1981)
6. Begg, B.D. and Vance, E.R., Mat. Res. Soc. Symp. Proc. Vol.465, 333–40 (1997).
7. Begg, B.D., Vance, E.R., Day, R.A., Hambley, M. and Conradson, S.D., Mat. Res. Soc. Symp. Proc. Vol.465, 325–32 (1997).
8. Vance, E. R., Lumpkin, G. R., Carter, M. L., Ball, C. J. andBegg, B. D., submitted to J. Am. Ceram. Soc.
9. Coelho, A.A., Cheary, R.W. and Smith, K.L., J. Solid State Chem. 129, 346359 (1997).
10. Clinard, F.W.,Jr., Hobbs, L.W., Land, C.C., Peterson, D.E., Rohr, D.L. and Roof, R.B., J. Nucl. Mater., 105 248256 (1982).
11. Clinard, F.W., Jr., Land, C.C., Peterson, D.E., Rohr, D.L. and Roof, R.B., in Scientific Basis for Nuclear Waste Management, ed., Topp, S.V. (North-Holland, New York, 1982) p 405.
12. Begg, B.D., Vance, E.R., Hunter, B.A. and Hanna, J.V., J. Mater. Res. 13(11) 3181–90 (1998).
13. Shannon, R.D., Acta Cryst. A32, 751 ((1976).
14. Bayliss, P., Mazzi, F., Munno, R. and White, T.J., Mineral. Mag. 53 565–69 (1989).
15. Subramanian, M.A., Aravamudan, G. and Rao, G.V. Subba, Prog. Solid St. Chem. 15 55143 (1983).

Structural Effect of Pu Substitutions on the Zr-Site in Zirconolite

  • B.D. Begg (a1), R.A. Day (a1) and A. Brownscombe (a1)

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