An ab initio study of the effect of charge localization on oxygen defect formation and migration energies in magnesium oxide
An ab initio study of the effect of charge localization on oxygen defect formation and migration energies in magnesium oxide
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从头算研究电荷局域化对氧化镁中氧缺陷形成和迁移能的影响
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
D. Duffy
中科院分区：
文献类型：
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作者：
J. Mulroue;D. Duffy
采用平面波密度泛函理论研究了MgO中不同电荷态的氧空位和杂质的性质。计算的性质是松弛的配置，Frenkel缺陷形成能和迁移势垒的能量，所有的属性被发现是强烈依赖于缺陷的电荷状态。O2−间隙原子的最低能量构型被发现是立方中心;然而，O−和O 0间隙原子形成哑铃构型。的弗伦克尔缺陷的能量也强烈依赖于缺陷的电荷，与中性对能量计算为3 eV低于双电荷弗伦克尔对缺陷的能量。发现随着氧空位净电荷的减少，氧空位的迁移势垒增加，这表明具有捕获电子的空位比经典势模型的F2+空位的移动的要小得多。氧化合物的迁移表现出特别有趣的行为。发现O 0间隙具有比O2−间隙更高的迁移势垒，但O−间隙的势垒非常低（0.06 eV）。该结果对经典辐射损伤模拟的可靠性具有重要影响。
Plane-wave density functional theory was used to study the properties of oxygen vacancies and interstitials, with different charge states, in MgO. The calculated properties were the relaxed configurations, the Frenkel defect formation energies and the energies of the migration barriers, and all properties were found to be strongly dependent on the defect charge state. The lowest energy configuration of the O2− interstitial was found to be the cube centre; however, the O− and O0 interstitials formed dumb-bell configurations. The Frenkel defect energies were also strongly dependent on the defect charge, with the neutral pair energy calculated to be 3 eV lower than the doubly charged Frenkel pair defect energy. The migration barriers of the oxygen vacancies were found to increase as the net charge of the oxygen vacancies decreased, which suggests that vacancies with trapped electrons are much less mobile than the F2+ vacancies modelled by classical potentials. The migration of the oxygen interstitials showed particularly interesting behaviour. The O0 interstitial was found to have a higher migration barrier than the O2− interstitial but a very low barrier (0.06 eV) was found for the O− interstitial. The results have significant implications for the reliability of classical radiation damage simulations.