Facile synthesis of Sm3+/Eu3+ codoped CeO2 ultrafine nanocrystals and oxygen vacancy site dependent photoluminescence

The mechanism of water-splitting and H2 production around the oxygen vacancy site of the LaMnO3 defective surface is explored for the purpose of quick identification of kinetically favorable dopants such as Mo.

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Diffusion of Fission Gas in Uranium Dioxide: A First-Principles Study

Volume 3: Nuclear Fuel and Material, Reactor Physics and Transport Theory; Innovative Nuclear Power Plant Design and New Technology Application ◽

10.1115/icone25-67365 ◽

2017 ◽

Author(s):

Qiang Zhao ◽

Zheng Zhang ◽

Yang Li ◽

Xiaoping Ouyang

Keyword(s):

Oxygen Vacancy ◽

Uranium Dioxide ◽

First Principles ◽

Density Functional ◽

Interstitial Site ◽

First Principles Calculation ◽

Spent Fuel ◽

Octahedral Interstitial Site ◽

Fission Gas ◽

Vacancy Site

Uranium dioxide (UO2) is the typical fuel that is used in nuclear fission reactor, fission gas are produced during and after the reactor operation, and the fission gas have a significant impact on the performance of UO2 in reactor. In this paper, we investigated the effects of the fission gas on the performance of UO2 by using the first-principles calculation method based on the density functional theory. The results are that, the volume of UO2 increased when there is a fission gas atom enter in UO2 supercell; fission gas prefer to occupy the octahedral interstitial site over the uranium vacancy site and the oxygen vacancy site, and the oxygen vacancy site is the most difficult occupied site due to the formation of an oxygen vacancy is more difficult than that of the uranium vacancy; our results of the UO2 elastic constants are in good agreement with other simulation results and experimental data, and the fission gas atoms make the ductility of UO2 decreased. Our works may shed some light on the development of the UO2 fuel and the spent fuel reprocessing.

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THEORETICAL STUDY OF N2O ADSORPTION AND DECOMPOSITION AT REGULAR AND DEFECT SITES OF MgO (001) SURFACE

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633603000367 ◽

2003 ◽

Vol 02 (01) ◽

pp. 57-64 ◽

Cited By ~ 8

Author(s):

YI-JUN XU ◽

JUN-QIAN LI ◽

YONG-FAN ZHANG

Keyword(s):

Oxygen Vacancy ◽

Density Functional ◽

Density Functional Method ◽

Functional Method ◽

Defect Sites ◽

Surface Oxygen Vacancy ◽

F Center ◽

Catalytic Reactivity ◽

Vacancy Site ◽

Mgo Surface

The adsorption of N 2 O at regular and defect sites of MgO (001) surface has been studied systematically using cluster models embedded in a large array of point charges by density functional method. The calculated results show that the MgO (001) surface with oxygen vacancies exhibits high catalytic reactivity toward N 2 O adsorptive-decomposition at variance with the regular MgO surface or the surface with magnesium vacancies. Much elongation of O–N bond of N 2 O after adsorption at oxygen vacancy site with O end of N 2 O down indicates that O–N bond has been broken with concurrent production of N 2, leaving a regular site instead of the original oxygen vacancy site (F center). Besides, the MgO (001) surface with magnesium vacancies hardly exhibits catalytic reactivity. It can be concluded that N 2 O dissociation is likely occurred at MgO (001) surface oxygen vacancy sites, which is consistent with the generally accepted viewpoint in the experiment.

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A Density Functional Theory Study on the Diffusion of Fission Gas Atoms in Uranium Dioxide

Journal of Nuclear Engineering and Radiation Science ◽

10.1115/1.4039885 ◽

2018 ◽

Vol 4 (3) ◽

Cited By ~ 1

Author(s):

Qiang Zhao ◽

Zheng Zhang ◽

Xiaoping Ouyang

Keyword(s):

Density Functional Theory ◽

Oxygen Vacancy ◽

Oxygen Atom ◽

Uranium Dioxide ◽

Density Functional ◽

Nuclear Reactor ◽

Functional Theory ◽

Fission Gas ◽

Vacancy Site ◽

He Atom

Uranium dioxide (UO2) is the typical fuel that is used in the current nuclear power plant; fission gas atoms are produced during and after the nuclear reactor operation; the fission gas atoms have a significant effect on the performance of UO2 fuel in the nuclear reactor. In this paper, we investigated the diffusion of the fission gas atoms in the UO2 fuel by using the first-principles calculation method based on the density functional theory (DFT). The results indicate that the volume of the UO2 cell increased when there is a fission gas atom enters in the UO2 supercell; the elastic properties of UO2 are in good agreement with other simulation results and experimental data and the fission gas atoms make the ductility of UO2 decreased; the fission gas atoms prefer to occupy the octahedral interstitial site (OIS) over the uranium vacancy site and the oxygen vacancy site, and the oxygen vacancy site is the most difficult occupied site due to the formation of an oxygen vacancy is more difficult than that of the uranium vacancy; the diffusion barrier of a He atom in the UO2 supercell is higher than that of an oxygen atom, that means that the diffusion of the He atom in UO2 fuel is weaker than that of the oxygen atom. Our works may shed some light on the formation mechanism of the bubbles caused by the fission gas atoms in the UO2 fuel.

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