Abstract
Thorium dioxide is of significant research interest for its use as a nuclear fuel, particularly as part of mixed oxide fuels. We present the results of a density functional theory (DFT) study of uranium-substituted thorium dioxide, where we found that increasing levels of uranium substitution increases the covalent nature of the bonding in the bulk ThO2 crystal. Three low Miller index surfaces have been simulated and we propose the Wulff morphology for a ThO2 particle and STM images for the (100), (110), and (111) surfaces studied in this work. We have also calculated the adsorption of a uranium atom and the U adatom is found to absorb strongly on all three surfaces, with particular preference for the less stable (100) and (110) surfaces, thus providing a route to the incorporation of uranium into a growing thoria particle.
| Original language | English |
|---|---|
| Pages (from-to) | 99-111 |
| Number of pages | 13 |
| Journal | Journal of Nuclear Materials |
| Volume | 473 |
| DOIs | |
| State | Published - May 1 2016 |
| Externally published | Yes |
Funding
Via our membership of the UK's HPC Materials Chemistry Consortium, which is funded by EPSRC ( EP/L000202 ), this work made use of the facilities of HECToR and ARCHER, the UK's national high-performance computing service, which is funded by the Office of Science and Technology through EPSRC's High End Computing Programme. This work used the UK Research Data Facility ( http://www.archer.ac.uk/documentation/rdf-guide ). AS gratefully acknowledges funding from AWE and the Molecular Modeling and Materials Science Centre for Doctoral Training at UCL, and NHdL thanks the Royal Society for an Industry fellowship and AWE for a William Penney fellowship. The authors thank James Pegg for many useful discussions.