Superionic transition in uranium dioxide: insights from molecular dynamics and lattice dynamics simulations
File(s)
Accepted version
Author(s)
Fossati, Paul CM
Burr, Patrick A
Cooper, Michael WD
Galvin, Conor OT
Grimes, Robin W
Type
Journal Article
Abstract
This study employs molecular dynamics (MD) simulations and lattice dynamics (LD) calculations to investigate the superionic transition in UO2, as well as the characteristics of the superionic phase. The superionic transition is found to be a second-order phase transition associated with an inflection point in enthalpy and lattice parameter at 2600 K. This resembles displacive phase transitions and is associated with an oxygen vibration mode becoming imaginary. The superionic state shows a combination of different local environments and dynamic features similar to glass-forming liquids. The analysis of its dynamics reveals seemingly contradictory characteristics: properties follow those of the lower-temperature crystalline phase in some respects, while exhibiting liquidlike behavior in others. The study highlights the complexity of the superionic phase, including heterogeneous mobility and diffusion mechanisms involving stringlike anion clusters.
Date Issued
2024-11
Date Acceptance
2024-10-30
Citation
Physical Review Materials, 2024, 8 (11)
ISSN
2475-9953
Publisher
American Physical Society
Journal / Book Title
Physical Review Materials
Volume
8
Issue
11
Copyright Statement
Copyright ©2024 American Physical Society
This is the author’s accepted manuscript made available under a CC-BY licence in accordance with Imperial’s Research Publications Open Access policy (www.imperial.ac.uk/oa-policy)
This is the author’s accepted manuscript made available under a CC-BY licence in accordance with Imperial’s Research Publications Open Access policy (www.imperial.ac.uk/oa-policy)
License URL
Identifier
https://doi.org/10.1103/physrevmaterials.8.115404
Publication Status
Published
Article Number
115404
Date Publish Online
2024-11-19