Abstract
The chemical and structural environments of f-electron elements in glasses are the origin of many of the important optical, electronic, and magnetic properties of materials incorporating these elements. Thus, the oxidation state and chemical coordination of lanthanides and actinides in host materials constitute an important design consideration in optically active glasses, magnetic materials, perovskite superconductors, and nuclear waste materials. We have made use of the characteristic line shapes of cerium to determine its oxidation state in alkali borosilicate glasses that are being developed for immobilization of plutonium. Cerium, it should be noted, is often used as a 'surrogate' element for plutonium in materials design because of its similar ionic size (for Pu in the + 3 and + 4 states) and preferred chemical coordination. The solubility of the plutonium (or cerium) in a waste glass will likely be determined by its redox state in the glass. By examining several compositions of prototype immobilization glass using electron energy loss spectroscopy (EELS), we found that the redox state of cerium doped to 7 wt% could be varied by a suitable choice of alkali elements in the glass formula. Preliminary results on plutonium-doped glasses confirm the design strategy employed, leading to 5 wt% (or more) plutonium being truly dissolved in the glass.
Original language | English |
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Pages (from-to) | 77-81 |
Number of pages | 5 |
Journal | Ultramicroscopy |
Volume | 67 |
Issue number | 1-4 |
DOIs | |
State | Published - Jun 1 1997 |
Externally published | Yes |
Event | Proceedings of the 1996 6th Conference on Frontiers in Electron Microscopy in Materials Science - Oak Brook, IL, USA Duration: Jun 4 1996 → Jun 7 1996 |
Funding
The authors wish to thank Lynn Boatner of Oak Ridge National Laboratory for providing the cerium and praseodymium orthophosphate samples and for engaging in useful discussions. This work supported by the Office of Environmental Management, US Department of Energy under Contract W-31-109-ENG-38.
Keywords
- Actinides
- Electron energy loss spectroscopy
- Glass
- Lanthanides