Structure stability of (U, Pu) C and (U, Pu) N compositions

Abstract Atomic scale computer simulations based on density functional theory (DFT) are used to calculate the formation energies and structures associated with phases in the U–N, Pu–N, U–C and Pu–C systems. Stable phases across the compositional spaces, from the metal to the nitrogen gas or graphite...

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Main Authors: William A. Watson, Sophie Cooper, Matthew Horton, Robin W. Grimes
Format: Article
Language:English
Published: Nature Portfolio 2025-06-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-03910-y
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author William A. Watson
Sophie Cooper
Matthew Horton
Robin W. Grimes
author_facet William A. Watson
Sophie Cooper
Matthew Horton
Robin W. Grimes
author_sort William A. Watson
collection DOAJ
description Abstract Atomic scale computer simulations based on density functional theory (DFT) are used to calculate the formation energies and structures associated with phases in the U–N, Pu–N, U–C and Pu–C systems. Stable phases across the compositional spaces, from the metal to the nitrogen gas or graphite end members, are identified using convex hull analysis. Many predicted phases correspond to those known from experimental phase diagrams (e.g. UN, U2N3; PuN; UC, U2C3; Pu2C3). However, many phases only sit on the convex hull upon inclusion of a suitably characterised Hubbard parameter (i.e. DFT + U). A nonstoichiometric composition of UN2−x is identified on the U–N convex hull but others, including stoichiometric UN2, are close to the line. A stoichiometric structure for Pu3C2 with $$R\overline{3}c$$ symmetry is identified, alongside which a nonstoichiometric PuC1−x phase has a similar energy.
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spelling doaj-art-691256d3e08940b38c4e3e0b12c85cea2025-08-20T02:30:41ZengNature PortfolioScientific Reports2045-23222025-06-0115111310.1038/s41598-025-03910-yStructure stability of (U, Pu) C and (U, Pu) N compositionsWilliam A. Watson0Sophie Cooper1Matthew Horton2Robin W. Grimes3Department of Materials, Imperial College LondonUnited Kingdom National Nuclear Laboratory LimitedUnited Kingdom National Nuclear Laboratory LimitedDepartment of Materials, Imperial College LondonAbstract Atomic scale computer simulations based on density functional theory (DFT) are used to calculate the formation energies and structures associated with phases in the U–N, Pu–N, U–C and Pu–C systems. Stable phases across the compositional spaces, from the metal to the nitrogen gas or graphite end members, are identified using convex hull analysis. Many predicted phases correspond to those known from experimental phase diagrams (e.g. UN, U2N3; PuN; UC, U2C3; Pu2C3). However, many phases only sit on the convex hull upon inclusion of a suitably characterised Hubbard parameter (i.e. DFT + U). A nonstoichiometric composition of UN2−x is identified on the U–N convex hull but others, including stoichiometric UN2, are close to the line. A stoichiometric structure for Pu3C2 with $$R\overline{3}c$$ symmetry is identified, alongside which a nonstoichiometric PuC1−x phase has a similar energy.https://doi.org/10.1038/s41598-025-03910-yUNPuNUCPuCDFTStructure stability
spellingShingle William A. Watson
Sophie Cooper
Matthew Horton
Robin W. Grimes
Structure stability of (U, Pu) C and (U, Pu) N compositions
Scientific Reports
UN
PuN
UC
PuC
DFT
Structure stability
title Structure stability of (U, Pu) C and (U, Pu) N compositions
title_full Structure stability of (U, Pu) C and (U, Pu) N compositions
title_fullStr Structure stability of (U, Pu) C and (U, Pu) N compositions
title_full_unstemmed Structure stability of (U, Pu) C and (U, Pu) N compositions
title_short Structure stability of (U, Pu) C and (U, Pu) N compositions
title_sort structure stability of u pu c and u pu n compositions
topic UN
PuN
UC
PuC
DFT
Structure stability
url https://doi.org/10.1038/s41598-025-03910-y
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