Local Environment of Iron and Uranium Ions in Vitrified Iron Phosphate Glasses Studied by Fe K and ULIII-edge X-Ray Absorption Fine Structure Spectroscopy

Mevlüt Karabulut
C. S. Ray, Missouri University of Science and Technology
M. Grimsditch
M.-L. Saboungi
George Daniel Waddill, Missouri University of Science and Technology
G. K. Marasinghe
P. G. Allen
C. H. Booth
J. J. Bucher
D. L. Caulder
D. K. Shuh
D. E. Day, Missouri University of Science and Technology

This document has been relocated to http://scholarsmine.mst.edu/matsci_eng_facwork/1444

There were 29 downloads as of 27 Jun 2016.


The local structure of iron and uranium ions in a series of iron phosphate glasses with the general composition (40 - x)Fe2O3-xUO2-60P2O5 and (1-x-y)(40Fe2O3-60P2O5)-xUO2-y(Na2O or CaO) was investigated using Fe K-edge and U LIII-edge x-ray absorption fine structure spectroscopy. Replacing Fe2O3 by UO2 in the glass caused more distortion in the coordination environment of Fe(III) ions. Extended x-ray absorption fine structure fits revealed that the Fe-P bonds observed in the base glass also existed in all the waste-loaded glasses. X-ray absorption near-edge structure showed that the uranium ions were predominantly present as U(IV) in the glasses. Uranium ions were coordinated to approximately 8 ± 1 oxygen atoms and 2.5 ± 0.6 phosphorus atoms at an average distance of 2.47 ± 0.02 and 3.8 ± 0.02 Å, respectively. There were no Fe-U or U-Fe neighbors observed, indicating that uranium ions occupied voids in the glass away from the PO4 units. These conclusions were supported by Mössbauer, x-ray photoelectron, and Raman spectroscopic data.