Crystalline ceramic based on the pyrochlore structure [(Ca,Gd,Hf,U,Pu) 2Ti2O7], has been proposed in the U.S. as a candidate waste form for the immobilization of weapons grade plutonium. Several samples of synthetic polycrystalline pyrochlore doped separately with 238Pu and 239Pu were studied using cathodoluminescence (CL) and electron probe microanalysis (EPMA) immediately after synthesis and then after 175, 245 and 405 days. The CL spectra of pyrochlore doped with 239Pu and 238Pu obtained immediately after ceramic synthesis and 175 days later were nearly the same and characterized by a typical broad band emission with a maximum peak centered at 2.5 eV. New CL peaks with maximum intensities at 2.0 and 2.3 eV in the emission spectra of 238Pu-and 239Pu-doped pyrochlore were observed 245 days later. It was determined that this newly formed CL peak at 2.3 eV is similar to one in CL spectrum of artificial standard glass doped with the uranyl ion, (UO2) 2+. It was suggested that CL band with maximum at 2.0 eV is caused by the U tetrahedral complex (UO4) 2-. Also, the same peaks were observed in the CL spectrum of natural U-rich pyrochlore containing approximately 23 wt.% U (mainly in the form of uranyl ion). The results obtained allow us to conclude that the radiation damage of pyrochlore-based ceramic waste form is accompanied with conversion of tetravalent uranium incorporated into pyrochlore structure to the mobile uranyl ion, (UO2) 2+, and complex (UO4)2-.
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I.W. Donald, B. L. Metcalfe and R.N. J. Taylor, J. Mater. Sci., 32, 5851 (1997).
S. E. Kesson and A. E. Ringwood, The Scientific Basis for Nuclear Waste Management VII, ed. G. McVay, Elsevier Science Publishing Co., New York, pp. 507–512 (1984).
A.B. Harker and J. F. Flintoff, The Scientific Basis for Nuclear Waste Management VII, ed. G. McVay, Elsevier Science Publishing Co., New York, pp. 513–520 (1984).
Morgan P. E. D., T. M. Shaw and E. A. Pugar, Advances in Ceramics, Vol. 8, edited by G. G. Wicks and W. A. Ross, Am. Ceram. Soc., Inc., Columbus, Ohio, pp. 209–221 (1984).
Morgan P. E. D., A. B. Harker, J. F. Flintoff, T. M. Shaw and D. R. Clarke, Advances in Ceramics Vol. 8, edited by G. G. Wicks and W. A. Ross, Amer. Ceram. Soc., Inc., Columbus, Ohio, pp. 234–246 (1984).
B. Ebbinghaus, R. VanKonynenburg, F. Ryerson, et al., Proc. Int. Symp. Waste Management-98, Tucson, AZ, USA, 1998, CD version, Rep.65-04 (1998).
B.E. Burakov, E.B. anderson, in Excess Weapons Plutonium Immobilization in Russia eds. L.J. Jardine, G.B. Borisov, UCRL-ID-138361, Proc. Meet. for Coordination and Review of Work, St. Petersburg, Russia, 1-4/11/1999, 167–179 (2000).
B. Burakov, E. anderson, in Immobilization of Excess Weapons Plutonium in Russia: A Review of LLNL Contract Work, eds. L.J. Jardine, G.B. Borisov, Proc. Meet. for Coordination and Review of Work, St. Petersburg, Russia, 13-16/11/2000, UCRL-ID-143846, 229–234 (2001).
M.V. Zamoryanskaya, B.E. Burakov, Mat. Res. Soc. Sym. Proc. (2001 in press)
A.M. Morozov, L.G. Morozova and P.P. Feofilov, Opt.Specry (in Russian), 32, 50 (1972).
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Zamoryanskaya, M.V., Burakov, B.E., Bogdanov, R.V. et al. A Cathodoluminescence Investigation of Pyrochlore, (Ca,Gd,Hf,U,Pu) 2Ti2O7, Doped with 238Pu and 239Pu. MRS Online Proceedings Library 713, 1129 (2001). https://doi.org/10.1557/PROC-713-JJ11.29