Local structure in solid solutions of stabilised zirconia with actinide dioxides (UO2, NpO2)

The local structure of (Zr,Lu,U)O2x and (Zr,Y,Np)O2x solid solutions has been investigated by extended X-ray absorption fine structure (EXAFS). Samples were prepared by mixing reactive (Zr,Lu)O2x and (Zr,Y)O2x precursor materials with the actinide oxide powders, respectively. Sintering at 1600 1C in Ar/H2 yields a fluorite structure with U(IV) and Np(IV). As typical for stabilised zirconia the metal–oxygen and metal–metal distances are characteristic for the different metal ions. The bond lengths increase with actinide concentration, whereas highest adaptation to the bulk stabilised zirconia structure was observed for U–O and Np–O bonds. The Zr–O bond shows only a slight increase from 2.14 ˚A at 6 mol% actinide to 2.18 ˚A at infinite dilution in UO2 and NpO2. The short interatomic distance between Zr and the surrounding oxygen and metal atoms indicate a low relaxation of Zr with respect to the bulk structure, i.e. a strong Pauling behaviour.

WALTER Marcus;  SOMERS Joseph;  BOUEXIERE Daniel;  ROTHE J.; 

2011-07-28

ACADEMIC PRESS INC ELSEVIER SCIENCE

JRC59601

0022-4596,   

www.elsevier.com/locate/jssc,    https://publications.jrc.ec.europa.eu/repository/handle/JRC59601,   

10.1016/j.jssc.2011.02.014,