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Inorganic Chemistry 45 (2006) 8408 -8413
Neutron Diffraction Studies of U$_4$O$_9$: Comparison with EXAFS Results
F. Garrido1, A.C. Hannon2, R.M. Ibberson2, L. Nowicki3, B.T.M. Willis4

Conradson et al.1 have analyzed X-ray absorption fine-structure spectra of the UO$_2$-U$_4$O$_9$ system and concluded that oxygen atoms are incorporated in U$_4$O$_9$ as oxo groups with U-O distances in the range 1.72-1.76 Å. They also found that the uranium sublattice consists of an ordered portion and an additional 'spectroscopically silent' glassy portion. We have carried out studies of powdered U$_4$O$_9$ by neutron diffraction which contradict these conclusions from EXAFS measurements. Our analysis shows that there are no U-O bonds shorter than 2.2 Å and that U4O9 is crystallographically ordered with no evidence of a glassy structure.
1 :  CSNSM - Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse
2 :  ISIS FACILITY - ISIS Facility, Rutherford Appleton Laboratory
3 :  THE ANDRZEJ SOLTAN INSTITUTE FOR NUCLEAR STUDIES - The Andrzej Soltan Institute for Nuclear Studies
4 :  CHEMISTRY RESEARCH LABORATORY - Chemistry Research Laboratory

Chimie/Chimie inorganique