Vacancy Formation Enthalpy in Polycrystalline Depleted Uranium

Lund, K.; Lynn, Kelvin G.; Weber, Marc H.; Okuniewski, Maria A.

doi:10.1088/1742-6596/443/1/012021

Cited by 9 publications

(5 citation statements)

References 7 publications

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“…Large variations with temperature only allow us to determine values in the range 1.3 eV < E f v < 2.6 eV. This range is close to that measured by the positron annihilation technique of Matter et al [65], 1.2 ± 0.25 eV, and even closer to that recently reported by Lund et al [66], 1.6 ± 0.16 eV. First-principles calculations of Xiang et al [15] produce a lower value of E f v = 1.08 eV, while Beeler et al [17] obtain 1.32 and 1.38 eV with different density functional approximations.…”

Section: Point Defectssupporting

confidence: 89%

On the accurate description of uranium metallic phases: a MEAM interatomic potential approach

Fernández

Pascuet

2014

Modelling Simul. Mater. Sci. Eng.

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A new interatomic potential in the framework of the modified embedded atom method (MEAM) to model U metal is presented. The potential acceptably reproduces the lattice parameters and cohesive energy of the orthorhombic αU. The relative stability of the experimentally observed phase at low temperatures with respect to several other structures (bct, bcc, simple cubic, tetragonal β Np, fcc and hcp) is also taken into account. Intrinsic point defect properties compare reasonably well with data from the literature. To determine the quality of the interaction, the potential is used to study a number of properties for the pure metal at finite temperatures and the results are compared with the available data. The obtained allotropic αU ↔ γU transformation and melting temperatures are in good agreement with experimental values. Based on the simulations, a new αU ↔ γU transformation mechanism is proposed.

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Section: Point Defectssupporting

confidence: 89%

On the accurate description of uranium metallic phases: a MEAM interatomic potential approach

Fernández

Pascuet

2014

Modelling Simul. Mater. Sci. Eng.

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“…The magnitude of for γ U found in MD mod eling turns out to be overestimated compared with the values found from static calculations by the DFT method [37,38] and from the positron annihilation vac SIA 1 1 1 ; [39,40]. The magnitudes of are within the energy range evaluated for interstials from static calculations in the DFT scope, i.e., from 0.5 to 1.5 eV [38] depending on the defect configuration.…”

Section: Introductionmentioning

confidence: 62%

Atomistic modeling of the self-diffusion in γ-U and γ-U-Mo

Smirnova

Kuksin

Starikov

et al. 2015

Phys. Metals Metallogr.

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Results of investigations of the self diffusion in gamma uranium and metallic U-Mo alloys are presented. Calculations are performed using the method of atomistic modeling with the help of interatomic potentials based on the embedded atom model and its modifications. Proposed potentials are verified by cal culating thermodynamic and mechanical properties of uranium and U-Mo alloys. The formation energies of point defects and atomic diffusivities due to the diffusion of defects are calculated for gamma uranium and alloy containing 9 wt % molybdenum. Self diffusion coefficients of uranium and molybdenum are evaluated. Based on the data obtained, it has been concluded that the experimentally observed features of the self diffu sion in gamma uranium can be explained by the prevalence of the interstitial mechanism.

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“…Also, it is possible to calculate vacancy formation energy at high pressures and T = 0 and extrapolate it to P = 0 [4]. The large variation in the experimentally determined vacancy formation energy in γ-uranium (1.2 eV [14]; 0-0.3 eV [15]; 1.6 eV [16,17]) does not allow to judge the correctness of such calculation methods.…”

Section: Introductionmentioning

confidence: 99%

Formation free energies of point defects and thermal expansion of bcc U and Mo

Smirnov¹,

Stegaĭlov²

2019

J. Phys.: Condens. Matter

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γ-U is a high temperature body-centred cubic (bcc) phase of uranium which is mechanically unstable at T = 0 K. The point defect properties in pure bcc uranium are not sufficiently well studied. In this work we use classical molecular dynamics simulations with the thermodynamic integration approach to calculate the formation free energies of vacancies and interstitials in bcc uranium and, for comparison, in bcc molybdenum. Contrary to the majority of other metals where the formation free energy is (much) higher for interstitials than for vacancies, our results show that in γ-uranium interstitials are the dominating type of defects in thermal equilibrium. We discuss the possible implications of this finding in the context of the thermal expansion data for γ-U that provide a certain supporting evidence.

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Vacancy Formation Enthalpy in Polycrystalline Depleted Uranium

Cited by 9 publications

References 7 publications

On the accurate description of uranium metallic phases: a MEAM interatomic potential approach

On the accurate description of uranium metallic phases: a MEAM interatomic potential approach

Atomistic modeling of the self-diffusion in γ-U and γ-U-Mo

Formation free energies of point defects and thermal expansion of bcc U and Mo

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