Abstract
An important challenge for modelling transport in materials for energy applications is that in most applications they are polycrystalline, and hence it is critical to understand the properties in the presence of grain boundaries. Moreover, most grain boundaries are not pristine stoichiometric interfaces and hence dopants are likely to play a significant role. In this paper, we describe our recent work on using atomistic molecular dynamics simulations to model the effect of doped grain boundaries on oxygen transport of fluorite structured UO 2. UO 2, much like other fluorite grain boundaries, are found to be sinks for oxygen vacancy segregation relative to the grain interior, thus facilitating oxygen transport. Fission products further enhance diffusivity via strong interactions between the impurities and oxygen defects. Doping produces a striking structural alteration in the Σ5 class of grain boundaries that enhances oxygen diffusivity even further. This article is part of a discussion meeting issue 'Energy materials for a low carbon future'.
| Original language | English |
|---|---|
| Article number | 20190026 |
| Pages (from-to) | 1-16 |
| Number of pages | 16 |
| Journal | Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences |
| Volume | 377 |
| Issue number | 2152 |
| Early online date | 8 Jul 2019 |
| DOIs | |
| Publication status | Published - 31 Aug 2019 |
Funding
Data accessibility. Force field parameters, atomic configurations, diffusion coefficients and Arrhenius plots can be found in the electronic supplementary material. Atomic density analysis and the mean squared displacements were carried out using the polypy code [76]. The data supporting the findings of this study are openly available at https://zenodo.org/record/3228371#.XOgEWBZKipo. Authors’ contributions. A.R.S. carried out the simulations, performed the data analysis and wrote the manuscript with contributions from all authors; S.C.P., M.M. and A.R.S. designed the study; M.M. and S.C.P. derived the force fields used in the study. Competing interests. The authors declare that they have no competing interests. Funding. A.R.S. acknowledges AWE and EPSRC (EP/R010366/1) for funding. Computations were run on Balena HPC facility at the University of Bath and the ARCHER UK National Supercomputing Service (http:// www.archer.ac.uk) via our membership of the UK’s HEC Materials Chemistry Consortium funded by EPSRC (EP/L000202, EP/R029431). Acknowledgements. M.M. thanks the University of Huddersfield for access to the Orion computing facility.
Keywords
- Fission products
- MO-doped UO
- Nuclear fuel
- Oxygen diffusion
- Segregation
- Space charge in UO
ASJC Scopus subject areas
- General Mathematics
- General Engineering
- General Physics and Astronomy