Quantum mechanical calculations of uranium phases and niobium defects in γ-uranium

Xiang, Shikai; Huang, Hanchen; Hsiung, L.M.

doi:10.1016/j.jnucmat.2007.11.003

Cited by 39 publications

(34 citation statements)

References 21 publications

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“…This is due to the fact that systems examined computationally have well-defined compositions and the influence of each change in condition can be analyzed separately. With increases in computational resources and both more powerful and more efficient algorithms, density functional theory (DFT) can be applied to larger systems and has been successfully used to examine defect formation in numerous materials [6][7][8][9][10], including UO 2 , with greater accuracy. For example, Petit and coworkers [11][12][13] used the local density approximation (LDA) and the generalized gradient approximation (GGA) to predict the energetics associated with point defect formation.…”

Section: Introductionmentioning

confidence: 99%

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Energetics of intrinsic point defects in uranium dioxide from electronic-structure calculations

Nerikar

Watanabe

Tulenko

et al. 2009

Journal of Nuclear Materials

128

106

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Section: Introductionmentioning

confidence: 99%

“…doi:10.1016/j.jnucmat.2008. 10.003 computational expense of modeling UO 2 . Despite these limitations, the importance of their work cannot be underestimated as these were the first calculations on UO 2 and showed that DFT could predict experimental trends successfully.…”

Section: Introductionmentioning

confidence: 99%

Energetics of intrinsic point defects in uranium dioxide from electronic-structure calculations

Nerikar

Watanabe

Tulenko

et al. 2009

Journal of Nuclear Materials

128

106

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“…Having presented and analyzed the electron distribution characteristic of α and γ phases of uranium, we start to study the defects in the γ-phase uranium. We considered three types of configurations: one single vacancy, one niobium atom occupying the substitutional site, and one niobium atom occupying the interstitial site [12]. Firstly, we investigate the one single vacancy in the γ-phase.…”

Section: Nb Defecting In γ-Phase Umentioning

confidence: 99%

FIRST-PRINCIPLES STUDY ON THE THERMODYNAMIC DEFECT AND CRYSTAL STRUCTURE OF U-12.5 AT% Nb ALLOY

Wang¹,

Wang²,

Wang³

et al. 2015

IJHT

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Depleted uranium will be stainless if a small amount of niobium was added into it, and niobium has good solubility in the γ-phase uranium. Upon cooling, it undergoes phase transformation. U-Nb alloys which is near the monotectoid have a finally martensitic (α") phase at room temperature if the content percent of niobium is from 5 to 8 w.t.%. First principles calculations have been performed to study how the niobium (Nb) atom defects into the γ-uranium and crystal structure of U-12.5 at% Nb alloy. Using DFT calculations, the authors find that the substitutional sites prefer to be occupied by Nb atoms thermodynamically in the γ-phase U. Furthermore, the crystal structure of U-12.5 at% Nb alloy is a monoclinic structure (α"), and the electronic structures characteristic reveals that the electron interactions between Nb atoms and U atoms in the alloy are mainly dominated by 4d orbital of Nb atom and 5f, 6d orbitals of U atom.

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“…Table 5. Energy of vacancy formation in γ U, eV EAM MD [19] 1.75 ab initio [8] 1.08 ab initio [9] 1.384 Experiment [34] 1.20 ± 0.25 New EAM potential 1.52…”

Section: Energy Of Vacancy Formationmentioning

confidence: 99%

“…In addition, in [6] Taylor obtained the value of the energy of vacancy formation in α U crystalline lattice. Xiang, Huang, and Hsiung [8], also used the pseudopotential method to calculate the properties of defects for the uranium-niobium system (including single vacancies in uranium). The results of a detailed analysis of possible defects (vacancies, inter stitial atoms) in the uranium crystalline phases are given in [9].…”

Section: Introductionmentioning

confidence: 99%

New interatomic potential for computation of mechanical and thermodynamic properties of uranium in a wide range of pressures and temperatures

Smirnova

Starikov

Stegaĭlov

2012

Phys. Metals Metallogr.

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A new interatomic potential for uranium is proposed. The potential is constructed in terms of the embedded atom method (EAM). As the reference data used for the optimization of potential functions, the values of forces, energies, and stresses obtained from ab initio computations have been employed. The poten tial has been applied for studies of properties of crystalline phases of uranium. It has been established that the lattice parameters of the α and γ phases, the elastic moduli, the isochore, the room temperature isotherm, and the energies of vacancy formation are in good agreement with the available experimental data and calculated results in the framework of the density functional theory. The potential suggested facilitates simulation of the first order phase transitions between γ uranium and liquid and between γ and α uranium. The melting points of uranium at pressures of up to 80 GPa, and the temperature of the phase transition between the γ phase and α phases, at ~3 GPa have been determined. For the first time, atomistic simulation of the phase transition between α and γ phases of uranium has been performed.

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Quantum mechanical calculations of uranium phases and niobium defects in γ-uranium

Cited by 39 publications

References 21 publications

Energetics of intrinsic point defects in uranium dioxide from electronic-structure calculations

Energetics of intrinsic point defects in uranium dioxide from electronic-structure calculations

FIRST-PRINCIPLES STUDY ON THE THERMODYNAMIC DEFECT AND CRYSTAL STRUCTURE OF U-12.5 AT% Nb ALLOY

New interatomic potential for computation of mechanical and thermodynamic properties of uranium in a wide range of pressures and temperatures

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