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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - The defect chemistry of non-stoichiometric PuO2±x
AU - Neilson, W.D.
AU - Pegg, J.T.
AU - Steele, H.
AU - Murphy, S.T.
PY - 2021/2/11
Y1 - 2021/2/11
N2 - An increased knowledge of the chemistry of PuO2is imperative for the design of procedures to store, dispose, or make use of PuO2. In this work, point defect concentrations in PuO2are determined by combining density functional theory (DFT) defect energies and empirical potential calculations of vibrational entropies. The obtained defect concentrations are expressed as a function of temperature and oxygen partial pressure and used to calculate non-stoichiometry in PuO2±x. The results show that the defect chemistry of PuO2is dominated by oxygen vacancies and interstitials. Hypo-stoichiometric PuO2−xis accommodated by both the uncharged oxygen vacancy and positively charged oxygen vacancy at small values ofx, withincreasingly dominant with increasingx. The negatively charged oxygen interstitial (O2−i) is found to accommodate hyper-stoichiometry (PuO2+x), but reluctance to form hyper-stoichiometric PuO2+xis observed, with oxygen interstitials present only in very low concentrations irrespective of conditions. The small degree of hyper-stoichiometry found is favoured by low temperatures. © the Owner Societies 2021.
AB - An increased knowledge of the chemistry of PuO2is imperative for the design of procedures to store, dispose, or make use of PuO2. In this work, point defect concentrations in PuO2are determined by combining density functional theory (DFT) defect energies and empirical potential calculations of vibrational entropies. The obtained defect concentrations are expressed as a function of temperature and oxygen partial pressure and used to calculate non-stoichiometry in PuO2±x. The results show that the defect chemistry of PuO2is dominated by oxygen vacancies and interstitials. Hypo-stoichiometric PuO2−xis accommodated by both the uncharged oxygen vacancy and positively charged oxygen vacancy at small values ofx, withincreasingly dominant with increasingx. The negatively charged oxygen interstitial (O2−i) is found to accommodate hyper-stoichiometry (PuO2+x), but reluctance to form hyper-stoichiometric PuO2+xis observed, with oxygen interstitials present only in very low concentrations irrespective of conditions. The small degree of hyper-stoichiometry found is favoured by low temperatures. © the Owner Societies 2021.
KW - Density functional theory
KW - Design for testability
KW - Stoichiometry
KW - Defect concentrations
KW - Empirical potentials
KW - Low concentrations
KW - Non-stoichiometric
KW - Oxygen interstitials
KW - Oxygen partial pressure
KW - Positively charged
KW - Vibrational entropy
KW - Oxygen vacancies
U2 - 10.1039/d0cp06497a
DO - 10.1039/d0cp06497a
M3 - Journal article
VL - 23
SP - 4544
EP - 4554
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
SN - 1463-9076
IS - 8
ER -