Structural, electronic, and elastic properties of equiatomic UZr alloys from first-principles

Zhang, Chengbin; Li, Xiuping; Li, Weidong; Zhang, Ping; Yin, Wen; Wang, Fangwei; Wang, Bao-Tian

doi:10.1016/j.jnucmat.2017.09.028

Cited by 5 publications

(10 citation statements)

References 61 publications

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“…Contrary to the conclusions from numerous past studies , it has been proposed in recent years that one must account for Coulomb repulsion in the electronic structure of the light actinide metals [28][29][30][31][32][33][34][35][36][37][38][39]. In these reports, a variety of U parameters are chosen, but a small U has largely been favored (U~1 eV).…”

Section: Introductionmentioning

confidence: 98%

“…Most of these DFT + U calculations [28][29][30][31][32][33][34][35][36][37][38][39] utilize plane-wave pseudopotential methods and because the obtained atomic volumes are smaller than expected, or for other reasons, one concludes a need for stronger electron correlation and employment of a Hubbard U. In this context, the improvement of the DFT + U volumes has been misinterpreted as a need for this type of electron correlation in the modeling, when in reality the situation reflects cancellation of errors.…”

Section: Introductionmentioning

confidence: 99%

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Assessing Relativistic Effects and Electron Correlation in the Actinide Metals Th to Pu

et al. 2019

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Density functional theory (DFT) calculations are employed to explore and assess the effects of the relativistic spin-orbit interaction and electron correlations in the actinide elements. Specifically, we address electron correlations in terms of an intra-atomic Coulomb interaction with a Hubbard U parameter (DFT + U). Contrary to recent beliefs, we show that for the ground-state properties of the light actinide elements Th to Pu, the DFT + U makes its best predictions for U = 0. Actually, our modeling suggests that the most popular DFT + U formulation leads to the wrong ground-state phase for plutonium. Instead, extending DFT and the generalized gradient approximation (GGA) with orbital-orbital interaction (orbital polarization; OP) is the most accurate approach. We believe the confusion in the literature on the subject mostly originates from incorrectly accounting for the spin-orbit (SO) interaction for the p 1/2 state, which is not treated in any of the widely used pseudopotential plane-wave codes. Here, we show that for the actinides it suffices to simply discard the SO coupling for the p states for excellent accuracy. We thus describe a formalism within the projector-augmented-wave (PAW) scheme that allows for spin-orbit coupling, orbital polarization, and non-collinear magnetism, while retaining an efficient calculation of Hellmann-Feynman forces. We present results of the ground-state phases of all the light actinide metals (Th to Pu). Furthermore, we conclude that the contribution from OP is generally small, but substantial in plutonium.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Assessing Relativistic Effects and Electron Correlation in the Actinide Metals Th to Pu

et al. 2019

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“…They proved that neither the Hubbard U nor the SOC is necessary for correctly describing U metal and U-Zr alloys. Moreover, in our previous work [ 40 ], the influence of DFT and DFT + U methods on the physical properties of various U-Zr alloy phases was also compared. The result revealed that DFT + U will not bring significant difference to the structural, electronic, magnetic, and elastic properties of U-Zr alloys.…”

Section: Introductionmentioning

confidence: 99%

“…Considering this fact, only the DFT method is adopted in the present work. In our previous work [ 40 ], we have investigated the physical properties of various U-Zr alloy phases, such as α-U and γ(U,Zr). As a promising candidate fuel for fast neutron reactors, U-Zr alloy will be exposed inevitably to the high-temperature environment.…”

Section: Introductionmentioning

confidence: 99%

“…According to the most recent phase diagram provided by Okamoto [ 41 ], at the elevated working temperature of nuclear fuel, U-Zr alloy should be the BCC γ phase. The structural and mechanical behavior of ordered-γ(U,Zr) has been investigated in our previous work [ 40 ]. However, the structural disorder is very common in alloy systems [ 13 , 37 ].…”

Section: Introductionmentioning

confidence: 99%

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Point Defects Stability, Hydrogen Diffusion, Electronic Structure, and Mechanical Properties of Defected Equiatomic γ(U,Zr) from First-Principles

Huang

Ma²,

Lai³

et al. 2022

Materials

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At present, many experimental fast reactors have adopted alloy nuclear fuels, for example, U-Zr alloy fuels. During the neutron irradiation process, vacancies and hydrogen (H) impurity atoms can both exist in U-Zr alloy fuels. Here, first-principles density functional theory (DFT) is employed to study the behaviors of vacancies and H atoms in disordered-γ(U,Zr) as well as their impacts on the electronic structure and mechanical properties. The formation energy of vacancies and hydrogen solution energy are calculated. The effect of vacancies on the migration barrier of hydrogen atoms is revealed. The effect of vacancies and hydrogen atom on densities of states and elastic constants are also presented. The results illustrate that U vacancy is easier to be formed than Zr vacancy. The H interstitial prefers the tetrahedral site. Besides, U vacancy shows H-trap ability and can raise the H migration barrier. Almost all the defects lead to decreases in electrical conductivity and bulk modulus. It is also found that the main effect of defects is on the U-5f orbitals. This work provides a theoretical understanding of the effect of defects on the electronic and mechanical properties of U-Zr alloys, which is an essential step toward tailoring their performance.

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Investigating the solution and diffusion properties of hydrogen inα-Uranium by first-principles calculations

Yang

Liu

et al. 2020

Progress in Nuclear Energy

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Structural, electronic, and elastic properties of equiatomic UZr alloys from first-principles

Cited by 5 publications

References 61 publications

Assessing Relativistic Effects and Electron Correlation in the Actinide Metals Th to Pu

Assessing Relativistic Effects and Electron Correlation in the Actinide Metals Th to Pu

Point Defects Stability, Hydrogen Diffusion, Electronic Structure, and Mechanical Properties of Defected Equiatomic γ(U,Zr) from First-Principles

Investigating the solution and diffusion properties of hydrogen inα-Uranium by first-principles calculations

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