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Empirical Identification of Uranium Oxides and Fluorides Using Electron Energy-loss Spectroscopy in the Transmission Electron Microscope

Published online by Cambridge University Press:  29 January 2003

Stephen B. Rice
Affiliation:
McCrone Associates, Inc., 850 Pasquinelli Drive, Westmont, IL 60559-5539
Hazel H. Bales
Affiliation:
McCrone Associates, Inc., 850 Pasquinelli Drive, Westmont, IL 60559-5539
John R. Roth
Affiliation:
McCrone Associates, Inc., 850 Pasquinelli Drive, Westmont, IL 60559-5539
Allen L. Whiteside
Affiliation:
McCrone Associates, Inc., 850 Pasquinelli Drive, Westmont, IL 60559-5539
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Abstract

Abstract: A set of uranium compound particles relevant to contaminated soils and other environmental concerns surrounding uranium bioavailability were studied by electron energy-loss spectroscopy (EELS). Core-loss EELS results suggest that uranium 4+ compounds have an energy loss resolvable from 6+ compounds. Shoulders on the uranium O4,5 edge further distinguish UO2 from UF4. Low-loss characteristics distinguish carbon-free uranium oxide specimens on holey substrates. In the presence of carbon, correction techniques must be applied. Uranium oxides, fluorides, and minerals show a tendency toward reduction of uranium toward 4+ under the beam. The electron dose required to achieve the transformation from 6+ to 4+ is more severe than that usually required to obtain satisfactory spectra, but the possibility for reduction should be considered. The conditions for low-loss analysis need not be as vigorous as those for core losses, and can be done without altering the valence of most oxides.

Type
Research Article
Copyright
2001 Cambridge University Press

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