Stability mechanism of cuboctahedral clusters in UO2+x:: First-principles calculations

被引：47

作者：

Geng, Hua Y. ^{[1
]}

Chen, Ying ^{[1
]}

Kaneta, Yasunori ^{[1
]}

Kinoshita, Motoyasu ^{[2
,3
]}

机构：

[1] Univ Tokyo, Dept Quantum Engn & Syst Sci, Tokyo 1138656, Japan

[2] Ctr Res Inst Elect Power Ind, Nucl Technol Res Lab, Tokyo 2018511, Japan

[3] Japan Atom Energy Agcy, Ibaraki 3191195, Japan

来源：

PHYSICAL REVIEW B | 2008年 / 77卷 / 18期

关键词：

D O I：

10.1103/PhysRevB.77.180101

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

The stability mechanism of cuboctahedral clusters in nonstoichiometric uranium dioxide is investigated by first-principles local density approximation with Hubbard correction method. Calculations reveal that the structural stability is inherited from U(6)O(12) Molecular cluster, whereas the energy gain through occupying its center with an additional oxygen makes the cluster win out by competition with point oxygen interstitials. Local displacement of the center oxygen along the < 111 > direction also leads the cluster eightfolded degeneracy and increases relatively the concentration at finite temperatures. However, totally, elevation of temperature, i.e., the effect of entropy, favors point interstitial over cuboctahedral clusters.

引用

页数：4

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