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.
Pyrochlore
plutonium
nuclear-waste
transmutation
Zirconia
near-edge structure
Conditioning
Minor actinides
EXAFS
spectroscopy
stabilized zirconia
Transmutation
uranium
x-ray-absorption
crystal-chemistry
Nuclear waste disposal
phase
Author
Catharina Nästrén
Chalmers, Chemical and Biological Engineering, Nuclear Chemistry
R. Jardin
European Commission (EC)
J. Somers
European Commission (EC)
M. Walter
European Commission (EC)
B. Brendebach
Karlsruhe Institute of Technology (KIT)
Journal of Solid State Chemistry
0022-4596 (ISSN) 1095-726X (eISSN)
Vol. 182 1 1-7DOI
10.1016/j.jssc.2008.09.017