Use of boiled hexamethylenetetramine and urea to increase the porosity of cerium dioxide microspheres formed in the internal gelation process
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Cerium dioxide (CeO2) is a commonly used simulant for plutonium dioxide and for plutonium (Pu) in a mixed uranium (U) and Pu oxide [(U, Pu)O2] in nuclear fuel development. This effort developed CeO2 microspheres with different porosities and diameters for use in a crush-strength study. The internal gelation technique has produced CeO2 microspheres with limited initial porosity. When an equal molar solution of urea and hexamethylenetetramine (HMTA) is gently boiling for 1 hr and used in the gelation process, the crystallite size and porosity of mixed U and thorium oxide microspheres and the (U, Pu)O2 microspheres increased significantly. In this study with cerium, the combination of ammonium cerium nitrate and 1-h boiled HMTA-urea failed to produce a stable feed broth. However, when the 1-h heated HMTA-urea was combined with unheated HMTA-urea in 1 to 3 volume ratio or the boiling time of the HMTA-urea was reduced to 15-20 min, a stable solution of HMTA, urea, and Ce was formed at 273 K. This new Ce solution produced CeO2 microspheres with much higher initial porosities. Intermediate porosities were possible when the heated HMTA/urea was aged prior to use.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1408648
- Alternate ID(s):
- OSTI ID: 1396929
- Journal Information:
- Journal of Nuclear Materials, Vol. 492, Issue C; ISSN 0022-3115
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Preparation of cerium dioxide microspheres by internal gelation with cerium citrate as precursor
|
journal | March 2019 |
Fabrication of CeO2–Nd2O3 microspheres by internal gelation process using M(OH)m and [MCit∙xH2O] (M=Ce3+, Ce4+, and Nd3+) as precursors
|
journal | July 2019 |
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