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Formation Gibbs free energy of point defects and oxygen clusters in uranium dioxide at high-pressure high-temperature conditions are calculated from first principles, using the LSDA+U approach for the electronic structure and the Debye…

Materials Science · Physics 2011-12-21 Hua Y. Geng , Hong X. Song , K. Jin , S. K. Xiang , Q. Wu

The stability mechanism of cuboctahedral clusters in nonstoichiometric uranium dioxide is investigated by first-principles LSDA+U method. Calculations reveal that the structural stability is inherited from U6O12 molecular cluster whereas…

Materials Science · Physics 2009-11-13 Hua Y. Geng , Ying Chen , Yasunori Kaneta , Motoyasu Kinoshita

Self-defect clusters in bulk matrix might affect the thermodynamic behavior of fission gases in nuclear fuel such as uranium dioxide. With first-principles LSDA+U calculations and taking xenon as a prototype, we find that the influence of…

Materials Science · Physics 2010-09-20 Hua Y. Geng , Ying Chen , Yasunori Kaneta , Motoyasu Kinoshita , Q. Wu

By first-principles LSDA+U calculations, we revealed that the current physical picture of defective uranium dioxide suggested solely by neutron diffraction analysis is unsatisfactory. An understanding based on quantum theory has been…

Materials Science · Physics 2009-11-13 Hua Y. Geng , Ying Chen , Yasunori Kaneta , Motoyasu Kinoshita

An atomistically informed mean field cluster dynamics model has been presented to investigate the nucleation and growth of defect loops in irradiated {\alpha}-U. TEM analysis of neutron irradiated {\alpha}-U shows the evolution of SIA and…

Materials Science · Physics 2023-07-17 Sanjoy Kumar Mazumder , Tiankai Yao , Anter El-Azab

At the atomic scale, uranium-plutonium mixed oxides (U,Pu)O_2 are characterized by cationic chemical disorder, which entails that U and Pu cations are randomly distributed on the cation sublattice. In the present work, we study the impact…

Point defects in diamond are of high interest as candidates for realizing solid state quantum bits, bioimaging agents, or ultrasensitive electric or magnetic field sensors. Various artificial diamond synthesis methods should introduce…

Materials Science · Physics 2016-09-14 Gergő Thiering , Adam Gali

Making use of the energetics and equations of state of defective uranium dioxide that calculated with first-principles method, we demonstrate a possibility of constraining the formation energy of point defects by measuring the transition…

Materials Science · Physics 2013-05-30 Hua Y. Geng , Hong X. Song , Q. Wu

A uniform distribution of point defects in an otherwise perfect crystallographic structure usually describes a unique pseudo phase of that state of a non-stoichiometric material. With off-stoichiometric uranium dioxide as a prototype, we…

Materials Science · Physics 2012-04-23 Hua Y. Geng , Hong X. Song , Q. Wu

The structural behavior of UO2 under high pressure up to 300GPa has been studied by first-principles calculations with LSDA+U approximation. The results show that a pressure-induced structural transition to the cotunnite-type (orthorhombic…

Materials Science · Physics 2007-05-23 H. Y. Geng , Y. Chen , Y. Kaneta , M. Kinoshita

In this work using the density functional theory (DFT), we have studied the structural, electronic and magnetic properties of uranium dioxide with antiferromagnetic 1k-, 2k-, and 3k-order structures. Ordinary approximations in DFT, such as…

Materials Science · Physics 2020-08-25 Samira Sheykhi , Mahmoud Payami

Uranium dioxide which is used as a fuel in light water nuclear reactors, is continually exposed to radiation damage originated from the collision of high-energy particles. Accumulation of the resulting defects gives rise to the evolution in…

Materials Science · Physics 2025-04-14 Mahmoud Payami , Samira Sheykhi , Mohammad-Reza Basaadat

The structures, point defects and impacts of fission products for U3Si (\b{eta}-U3Si and {\gamma}-U3Si) and USi2 ({\alpha}-USi2 and \b{eta}-USi2) are studied by first-principles calculations. The lattice parameters of U3Si and USi2 are…

Nuclear Theory · Physics 2017-01-19 Miao He , Shiyu Du , Heming He , Jiajian Lang , Zhen Liu , Qing Huang , Cheng-Te Lin , Ruifeng Zhang , Dejun Wang

The paper presents a model for liquid uranium dioxide, obtained by improving a simplified ionic model, previously adopted to describe the equation of state of this substance [1]. A "chemical picture" is used for liquid UO2 of stoichiometric…

We aim to understand the formation of cloud condensation nuclei in oxygen-rich substellar atmospheres by calculating fundamental properties of the energetically most favorable vanadium oxide molecules and clusters. A hierarchical…

Earth and Planetary Astrophysics · Physics 2024-10-02 Helena Lecoq-Molinos , David Gobrecht , J. P. Sindel , Christiane Helling , Leen Decin

By applying a genetic algorithm in a cascade approach of increasing accuracy, we calculate the composition and structure of MgMOx clusters at realistic temperatures and oxygen pressures. The stable and metastable systems are identified by…

To explore the formation of noncollinear magnetic configurations in materials with strongly correlated electrons, we derive a noncollinear LSDA+$U$ model involving only one parameter $U$, as opposed to the difference between the Hubbard and…

Strongly Correlated Electrons · Physics 2019-08-21 S. L. Dudarev , P. Liu , D. A. Andersson , C. R. Stanek , T. Ozaki , C. Franchini

The formalism of electronic density-functional-theory, with Hubbard-U corrections (DFT+U), is employed in a computational study of the energetics of U_{1-x} Ce_x O_2 mixtures. The computational approach makes use of a procedure which…

Materials Science · Physics 2012-03-08 B. E. Hanken , C. R. Stanek , N. Grønbech-Jensen , M. Asta

Defects are crucial in determining a variety of material properties especially in low dimensions. In this work, we study point defects in monolayer alpha-phase Ruthenium (III) chloride (alpha-RuCl3), a promising candidate to realize quantum…

Materials Science · Physics 2023-05-31 Wenqi Yang , Linghan Zhu , Yan Lu , Erik Henriksen , Li Yang

La1-xCaxMnO3+delta and La1-xNaxMnO3+delta samples with well defined cation molecularity and oxygen contents are analyzed with XRPD, electrical conductivity, electron paramagnetic resonance and static magnetization measurements. Point…

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