Ab initio study of H, B, C, N, O, and self-interstitial atoms in hcp-Zr

You, Daegun; Ganorkar, Shraddha; Joo, Minsoo; Park, Donghyun; Kim, Sooran; Kang, Keonwook; Lee, Dongwoo

doi:10.1016/j.jallcom.2019.02.144

Cited by 14 publications

(6 citation statements)

References 36 publications

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“…As shown in Table 2, the most stable occupancy for an O atom in ω-Zr is an Octa position, corresponding to a formation energy of −5.97 eV, and the second most stable occupancy is a Tetra position, corresponding to a formation energy of −4.62 eV. Our calculations are in agreement with the values obtained by You et al [37]. We investigated the diffusion behavior of O atoms in ω-Zr using the CI-NEB method.…”

Section: Oxygen In ω-Zrsupporting

confidence: 91%

“…It can be seen that our calculated lattice parameters are in good agreement with the experimental data and other theoretical calculations. It is well known that oxygen occupies mainly the interstitial positions in Zr [37], so we mainly consider the case where oxygen (O) is located at interstitial positions in ω-Zr. As shown in Figure 1, there are five main high-symmetry interstitial positions in ω-Zr: 1b(0, 0, 1 2 ), 2c( 2 3 , 1 3 , 0), 2e(0, 0, z), 3f(0, 1 2 , 0), and 3g( 1 2 , 1 2 , 1 2 ).…”

Section: Oxygen In ω-Zrmentioning

confidence: 99%

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First-Principles Study of Oxygen in ω-Zr

Chen

Liu

Wang

et al. 2023

Metals

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Zirconium alloys, which are widely used as cladding materials in nuclear reactors, are prone to react with oxygen (O). Furthermore, the ω-Zr in zirconium alloys can significantly increase the strength and hardness of these alloys, but there is a lack of reports on the behavior of oxygen in ω-Zr in the current literature. To investigate their interactions, we have studied the behavior of O in ω-Zr using the first-principles approach. In this work, we examined the effects of vacancy and alloying elements (Nb, Sn) on the behavior of O in ω-Zr. The results show that O with a formation energy of −5.96 eV preferentially occupies an octahedral interstitial position in ω-Zr. A vacancy reduces the formation energy of O in a tetrahedral interstitial position in ω-Zr. Nb and Sn decrease the formation energy of O in the octahedral interstitial position by 6.16 eV and 5.08 eV. Vacancy effectively reduces the diffusion barrier of O around it, which facilitates the diffusion of O in ω-Zr. Nb and Sn preferentially occupy the 1b and 2d substitution sites in ω-Zr, respectively. Nb makes the diffusion barrier of O in ω-Zr lower and promotes the diffusion of O in ω-Zr. Moreover, Sn makes the diffusion of O around Sn difficult. It was further found that O is less prone to form clusters in ω-Zr and tends to independently occupy interstitial positions in ω-Zr. In particular, a single vacancy would make the binding energy between O atoms to be further reduced.

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Section: Oxygen In ω-Zrsupporting

confidence: 91%

Section: Oxygen In ω-Zrmentioning

confidence: 99%

First-Principles Study of Oxygen in ω-Zr

Chen

Liu

Wang

et al. 2023

Metals

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“…According to our calculations, the formation energy of N atom at the sub position is 2.99 eV, followed by 1.93 eV and 0.51 eV for C and O atoms, respectively. Recently Daegun et al [19] studied the occupations of single C, N or O atom in four different interstitial sites of hcp-Zr, respectively. As also shown in figure 2, our results agree well with those obtained by Daegun.…”

Section: Impurities In Hcp-zrmentioning

confidence: 99%

“…For hexagonal-closed packed Zr (hcp-Zr), the effect of the C, N and O impurities on hydrogen has not been systematically studied yet. Daegun et al [19] studied six types of placeholders of C, N and O impurities, but their work still missed some other interstitial positions. In addition, the inter-impurity interaction and the effects of impurities on the H behavior are not well understood.…”

Section: Introductionmentioning

confidence: 99%

Interaction between impurity elements (C, N and O) and hydrogen in hcp-Zr: a first-principles study

Feng¹,

Liu²,

Liu³

et al. 2020

Modelling Simul. Mater. Sci. Eng.

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Zirconium (Zr) alloys as cladding materials are widely used in fission reactors. The service life of Zr-based materials cladding is seriously affected by the hydrogen (H) behaviors; while the impurities (C, N and O) in Zr alloys have a great influence on the hydrogen behaviors. In this work, we have investigated the impurity–hydrogen interactions in hexagonal-closed packed Zr (hcp-Zr) by a first-principles approach. It was found that H atom tends to occupy tetrahedral interstitial position in perfect Zr and occupy octahedral interstitial position in Zr with vacancy, while the impurities tend to occupy octahedral interstitial positions in Zr both with and without vacancy. The impurities can trap H atoms. Four possible paths were studied for the diffusion of H atom in hcp-Zr, and it is found that the diffusion barriers of H varied with the presence of impurities.

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“…Another DFT study [ 21 ] indicates that the diffusion direction of the interstitial C and O impurities in the α-Zr is not the same—oxygen interstitials prefer diffusion along c-axis, while carbon diffuses along both a and c axes.…”

Section: Introductionmentioning

confidence: 99%

Crystal Lattice Defects in Deuterated Zr in Presence of O and C Impurities Studied by PAS and XRD for Electron Screening Effect

Kowalska,

Czerski,

Horodek

et al. 2023

Materials

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Low-energy nuclear reactions are known to be extremely dependent on the local crystal structure and crystal defects of the deuterated samples. This has a strong influence on both hydrogen diffusion and the effective electron mass. The latter determines the strength of the local electron-screening effect and can change the deuteron–deuteron reaction rates at very low energies by many orders of magnitude. In the present study, zirconium samples were exposed to various conditions and energies of deuteron beams using the unique accelerator system with ultra-high vacuum, installed in the eLBRUS laboratory at the University of Szczecin. Irradiated and virgin samples were investigated by means of the X-ray diffraction (XRD) and positron annihilation spectroscopy (PAS). While the first method delivers information about changes of crystal lattice parameters and possible production of hydrides accompanying the formation of dislocations that are produced during irradiation of the samples, the second one can determine the depth distribution of crystal defects, being especially sensitive to vacancies. The studied Zr samples were also implanted by carbon and oxygen ions in order to simulate the real situation taking place in nuclear reaction experiments and to investigate their influence on the kinetic of produced vacancies. The observed enhancement of the electron-screening effect in the deuteron fusion reaction at very low energies could be explained by formation of a high number of vacancies during the deuteron irradiation of samples. Possible carbon and oxygen impurities can affect this process in various ways by changing the depth distribution of vacancies and their diffusion, but they play only a minor role in the strength of the electron-screening effect.

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Ab initio study of H, B, C, N, O, and self-interstitial atoms in hcp-Zr

Cited by 14 publications

References 36 publications

First-Principles Study of Oxygen in ω-Zr

First-Principles Study of Oxygen in ω-Zr

Interaction between impurity elements (C, N and O) and hydrogen in hcp-Zr: a first-principles study

Crystal Lattice Defects in Deuterated Zr in Presence of O and C Impurities Studied by PAS and XRD for Electron Screening Effect

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