Energetics of halogen impurities in thorium dioxide

Navaratnarajah Kuganathan, Partha S. Ghosh, Ashok K. Arya, Gautam K. Dey, Robin W. Grimes

Research output: Contribution to journalArticle

3 Citations (Scopus)
4 Downloads (Pure)

Abstract

Defect energies for halogen impurity atoms (Cl, Br and I) in thoria are calculated using the generalized gradient approximation and projector augmented plane wave potentials under the framework of density functional theory. The energy to place a halogen atom at a pre-existing lattice site is the incorporation energy. Seven sites are considered: octahedral interstitial, O vacancy, Th vacancy, Th-O di-vacancy cluster (DV) and the three O-Th-O tri-vacancy cluster (NTV) configurations. For point defects and vacancy clusters, neutral and all possible defect charge states up to full formal charge are considered. The most favourable incorporation site for Cl is the singly charged positive oxygen vacancy while for Br and I it is the NTV1 cluster. By considering the energy to form the defect sites, solution energies are generated. These show that in both ThO2-x and ThO2 the most favourable solution equilibrium site for halides is the single positively charged oxygen vacancy (although in ThO2, I demonstrates the same solubility in the NTV1 and DV clusters). Solution energies are much lower in ThO2-x than in ThO2 indicating that stoichiometry is a significant factor in determining solubility. In ThO2, all three halogens are highly insoluble and in ThO2-x Br and I remain insoluble. Although ½Cl2 is soluble in ThO2-x alternative phases such as ZrCl4 exist which are of lower energy.

Original languageEnglish
Pages (from-to)192-201
Number of pages10
JournalJournal of Nuclear Materials
Volume495
Early online date17 Aug 2017
DOIs
Publication statusPublished - 1 Nov 2017
Externally publishedYes

Fingerprint

Thoria
Thorium Dioxide
Halogens
thorium
dioxides
halogens
Vacancies
Impurities
impurities
Oxygen vacancies
Defects
Solubility
energy
Atoms
defects
solubility
Point defects
Stoichiometry
Density functional theory
oxygen

Bibliographical note

© 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/).

Keywords

  • Defects
  • DFT
  • Halogen
  • Nuclear fuel
  • Thoria

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Materials Science(all)
  • Nuclear Energy and Engineering

Cite this

Energetics of halogen impurities in thorium dioxide. / Kuganathan, Navaratnarajah; Ghosh, Partha S.; Arya, Ashok K.; Dey, Gautam K.; Grimes, Robin W.

In: Journal of Nuclear Materials, Vol. 495, 01.11.2017, p. 192-201.

Research output: Contribution to journalArticle

Kuganathan, Navaratnarajah ; Ghosh, Partha S. ; Arya, Ashok K. ; Dey, Gautam K. ; Grimes, Robin W. / Energetics of halogen impurities in thorium dioxide. In: Journal of Nuclear Materials. 2017 ; Vol. 495. pp. 192-201.
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