Actinide incorporation in a zirconia based pyrochlore (Nd(1.8)An(0.2))Zr2O7+x (An = Th, U, Np, Pu, Am)
Journal article, 2009

Actinides (thorium, uranium, neptunium, plutonium, and americium) were infiltrated into a porous Nd1.8Zr2O6.7 matrix, prepared by gel-supported precipitation. (Nd(1.8)An(0.2))Zr2O7+x pyrochlores were formed after sintering in Ar/H-2 and the pyrochlore structure remains during oxidation at 800 degrees C in air. X-ray diffraction reveals a linear relationship between the pyrochlore lattice parameter and the ionic radii of the actinides. EXAFS measurements on actinide L-3-edge show a split shell of nearest neighbour oxygen atoms similar to that Surrounding of Nd. The actinide-oxygen bond distances decrease with the actinide ionic radii, which verifies that these actinides adopt the Nd site in the (Nd(1.8)An(0.2))Zr2O7+x pyrochlore. The oxidation susceptibility of Np is related to the availability of oxygen vacancies and in contrast to stabilised zirconia Np(V) can be obtained in zirconia based pyrochlore. (C) 2008 Elsevier Inc. All rights reserved.

Transmutation

plutonium

spectroscopy

stabilized zirconia

x-ray-absorption

uranium

Nuclear waste disposal

Minor actinides

phase

nuclear-waste

Zirconia

EXAFS

transmutation

near-edge structure

crystal-chemistry

Pyrochlore

Conditioning

Author

Catharina Nästrén

Chalmers, Chemical and Biological Engineering, Nuclear Chemistry

R. Jardin

Joint Research Centre (JRC), European Commission

J. Somers

Joint Research Centre (JRC), European Commission

M. Walter

Joint Research Centre (JRC), European Commission

B. Brendebach

Karlsruhe Institute of Technology (KIT)

Journal of Solid State Chemistry

0022-4596 (ISSN) 1095-726X (eISSN)

Vol. 182 1 1-7

DOI

10.1016/j.jssc.2008.09.017

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