Title: Charge Distribution and Local Structure and Speciation in the UO2+x and PuO2+x Binary Oxides for x <0.25.
Authors: CONRADSON S.d.BEGG B.d.CLARK D.l.DEN AUWER C.DING M.DORHOUT P.k.ESPINOSA-FALLER J.GORDON P.HAIRE R.g.HESS N.j.HESS R.f.WEBSTER KEOAGH D.LANDER GerardMANARA DARIOMORALES L.a.NEU M.p.PAVIET-HARTMANN P.REBIZANT JEANRONDINELLA VINCENZORUNDE W.DREW TAIT C.KIRK VEIRS D.VILLELLA P.m.WASTIN FRANCK
Citation: JOURNAL OF SOLID STATE CHEMISTRY vol. 178 p. 521-535
Publisher: ELSEVIER SCI LTD
Publication Year: 2005
JRC Publication N°: JRC30033
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC30033
Type: Articles in Journals
Abstract: The local structure and chemical speciation of the mixed valence, fluorite based oxides UO2+x (0.00pxp0.20) and PuO2+x PuO2+xy(OH)2y zH2O have been determined by U Pu LIII XAFS spectroscopy. The U spectra indicate (1) that the O atoms are incorporated as oxo groups at short (1.75A) U O distances consistent with U(VI) concomitant with a large range of U displacements that reduce the apparent number of U neighbors and (2) that the UO2 fraction remains intact implying that these O defects interact to form clusters and give the heterogeneous structure consistent with the diffraction patterns. The PuO2+x system, which does not show a separate phase at its x 1:4 0:25 endpoint, also displays (1) oxo groups at longer 1.9A distances consistent with Pu(V+d), (2) a multisite Pu O distribution even when x is close to zero indicative of the formation of stable species with H2O and its hydrolysis products with O2, and (3) a highly disordered, spectroscopically invisible Pu Pu component. The structure and bonding in AnO2+x are therefore more complicated than have previously been assumed and show both similarities but also distinct differences among the different elements.
JRC Institute:Institute for Transuranium Elements

Files in This Item:
There are no files associated with this item.


Items in repository are protected by copyright, with all rights reserved, unless otherwise indicated.