Fission gas in thoria

Kuganathan, Navaratnarajah; Ghosh, P. S.; Galvin, C.O.T.; Arya, A.; Dutta, B.K.; Dey, G.K.; Grimes, Robin W.

doi:10.1016/j.jnucmat.2016.12.011

Cited by 14 publications

(13 citation statements)

References 33 publications

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“…In previous work [21] we partially demonstrated the validity of the parameters by showing the good correspondence between predicted and experiment values for lattice constants and bulk modulus for Th and ThO 2 .…”

Section: Calculation Methodologiessupporting

confidence: 52%

“…Charged defects interact with their next periodic images. In our previous study [21] we described the methodology as implemented by Makov et al [27] to compensate for image charges when calculating defect formation energies.…”

Section: Calculation Methodologiesmentioning

confidence: 99%

“…Some atomic scale modelling studies on trapping and diffusion of the volatile fission products (Xe, Br, Rb and Cs) [18,20] have been reported but these only considered the incorporation of impurity atoms in neutral point defects and neutral clusters of defects, leaving aside the possibility of incorporation in charged defect configurations. A more extensive study of Xe and Kr has been made [21], which did consider charged as well as neutral defect sites. This also considered solution in stoichiometric ThO 2 and substoichiometric ThO 2-x .…”

Section: Introductionmentioning

confidence: 99%

“…The study here focuses on the stability and chemical interaction of halogen impurity atoms (Cl, Br and I) in thoria by considering seven incorporation sites for these atoms: the octahedral interstitial, O vacancy, Th vacancy, Th-O di-vacancy cluster (DV) and the OTh-O neutral tri-vacancy cluster (NTV) (for which there are three configurations [21]). For point defects and vacancy clusters, both neutral and all charged defect configurations, up to full formal charge, are considered for the calculation of incorporation energies (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…Incorporation energies are then used as the basis for calculating solution energies by considering the energy to form the defect (trap) site. This assumes that the concentration of halogen ions is greater than the availability of defect sites (which is appropriate for all but the very lowest defect concentrations [21]). The effect of van der Waals (vdW) interactions is considered and included for all possible defect configurations.…”

Section: Introductionmentioning

confidence: 99%

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Energetics of halogen impurities in thorium dioxide

Kuganathan

Ghosh

Arya

et al. 2017

Journal of Nuclear Materials

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a b s t r a c tDefect 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 ThO 2-x and ThO 2 the most favourable solution equilibrium site for halides is the single positively charged oxygen vacancy (although in ThO 2 , I demonstrates the same solubility in the NTV1 and DV clusters). Solution energies are much lower in ThO 2-x than in ThO 2 indicating that stoichiometry is a significant factor in determining solubility. In ThO 2 , all three halogens are highly insoluble and in ThO 2-x Br and I remain insoluble. Although ½Cl 2 is soluble in ThO 2-x alternative phases such as ZrCl 4 exist which are of lower energy.

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Section: Calculation Methodologiessupporting

confidence: 52%

Section: Calculation Methodologiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Energetics of halogen impurities in thorium dioxide

Kuganathan

Ghosh

Arya

et al. 2017

Journal of Nuclear Materials

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Targeting Vacancies in Nitridosilicates: Aliovalent Substitution of M²⁺ (M=Ca, Sr) by Sc³⁺ and U³⁺

et al. 2018

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Based on the known linking options of their fundamental building unit, that is the SiN4 tetrahedron, nitridosilicates belong to the inorganic compound classes with the greatest structural variability. Although facilitating the discovery of novel Si–N networks, this variability represents a challenge when targeting non‐stoichometric compounds. Meeting this challenge, a strategy for targeted creation of vacancies in highly condensed nitridosilicates by exchanging divalent M2+ for trivalent M3+ using the ion exchange approach is reported. As proof of concept, the first Sc and U nitridosilicates were prepared from α‐Ca2Si5N8 and Sr2Si5N8. Powder X‐ray diffraction (XRD) and synchrotron single‐crystal XRD showed random vacancy distribution in Sc0.2Ca1.7Si5N8, and partial vacancy ordering in U0.5xSr2−0.75xSi5N8 with x≈1.05. The high chemical stability of U nitridosilicates makes them interesting candidates for immobilization of actinides.

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Targeting Vacancies in Nitridosilicates: Aliovalent Substitution of M²⁺ (M=Ca, Sr) by Sc³⁺ and U³⁺

et al. 2018

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Fission gas in thoria

Cited by 14 publications

References 33 publications

Energetics of halogen impurities in thorium dioxide

Energetics of halogen impurities in thorium dioxide

Targeting Vacancies in Nitridosilicates: Aliovalent Substitution of M²⁺ (M=Ca, Sr) by Sc³⁺ and U³⁺

Targeting Vacancies in Nitridosilicates: Aliovalent Substitution of M²⁺ (M=Ca, Sr) by Sc³⁺ and U³⁺

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Fission gas in thoria

Cited by 14 publications

References 33 publications

Energetics of halogen impurities in thorium dioxide

Energetics of halogen impurities in thorium dioxide

Targeting Vacancies in Nitridosilicates: Aliovalent Substitution of M2+ (M=Ca, Sr) by Sc3+ and U3+

Targeting Vacancies in Nitridosilicates: Aliovalent Substitution of M2+ (M=Ca, Sr) by Sc3+ and U3+

Contact Info

Product

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Targeting Vacancies in Nitridosilicates: Aliovalent Substitution of M²⁺ (M=Ca, Sr) by Sc³⁺ and U³⁺

Targeting Vacancies in Nitridosilicates: Aliovalent Substitution of M²⁺ (M=Ca, Sr) by Sc³⁺ and U³⁺