Oxygen Vacancies in CrO2: The Influences to Half Metallicity and the Formation Mode
Oxygen Vacancies in CrO2: The Influences to Half Metallicity and the Formation Mode
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CrO2中氧空位：对半金属丰度的影响及其形成模式
DOI：
10.1109/tmag.2016.2562610
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发表时间：
2016
影响因子：
2.1
通讯作者：
Shi Jing
中科院分区：
文献类型：
--
作者：
Liu Shuo;Lu Zhihong;Yuan Cheng;Guo Fang;Xiong Rui;Shi Jing
采用基于密度泛函理论的第一性原理计算方法研究了不同氧空位浓度和分布的CrO 2的电子结构.结果表明，在较高的空位浓度下，只要氧空位不在同一八面体中配对，CrO 2的半金属性就保持不变;当两个空位出现在一个八面体中时，CrO 2的半金属性就会受到严重削弱，甚至在较低的空位浓度下也会被完全破坏，这取决于空位对的构型。我们的研究结果表明，CrO 2的半金属度是更敏感的氧空位的相对位置比空位浓度。通过研究形成能的位置依赖性，讨论了氧空位的形成和扩展方式。结果表明，一旦一个氧空位形成，下一个氧空位往往出现在同一八面体的赤道面，将Cr 4+还原为Cr 3+。这种配对性质表明，氧空位可能倾向于以平面模式沿着[00 l]方向扩散。
The electronic structures of chromium dioxide (CrO2) with different concentrations and distributions of oxygen vacancy were investigated by first-principle calculations based on density functional theory. It was found that even at fairly high vacancy concentration, the half metallicity of CrO2 keeps intact as long as oxygen vacancies do not pair in the same octahedron; when two vacancies appear in one octahedron, the half metallic nature of CrO2 may be severely weakened or completely destroyed even at much lower vacancy concentration depending on the vacancy-pair configuration. Our results suggest that the half metallicity of CrO2 is more sensitive to the relative positions of oxygen vacancies than to the vacancy concentration. By investigating the position dependence of the formation energy, the formation and the spreading mode of oxygen vacancies were discussed. The results show that once an oxygen vacancy forms, the next oxygen vacancy tends to appear in the equatorial plane of the same octahedron to reduce Cr4+ to Cr3+. This kind of pairing nature indicates that the oxygen vacancies may tend to spread in a planar mode along the [00l] direction.