金红石型TiO2中点缺陷的屏蔽交换杂化泛函计算
Calculation of point defects in rutile TiO2 by the Screened Exchange Hybrid Functional
摘要：
采用屏蔽交换（sX）混合密度泛函方法计算了金红石型TiO2中氧空位和钛间隙的形成能，得到的禁带宽度为3.1 eV，与实验值接近.的O空位引起的间隙状态躺在0.7 eV以下的导带边缘，其电荷密度是本地化周围的两个三个Ti原子旁边的空位。Ti间隙在带隙中产生四个缺陷态，其未成对电子位于间隙和相邻的Ti 3d轨道上。对于贫氧化学势，中性O空位的形成能为1.9 eV，与中性Ti间隙的形成能相似，并且对于富氧条件下的Ti间隙具有较低的形成能。这表明O空位和Ti间隙都与金红石型TiO 2中的氧缺乏有关，但在富O条件下O空位将占主导地位。这解决了文献中关于缺陷定位和缺陷优势的问题。
英文摘要：
The formation energies of the oxygen vacancy and titanium interstitial in rutile TiO2 were calculated by the screened exchange (sX) hybrid density functional method, which gives a band gap of 3.1 eV, close to the experimental value. The O vacancy gives rise to a gap state lying 0.7 eV below the conduction band edge, whose charge density is localised around the two of three Ti atoms next to the vacancy. The Ti interstitial generates four defect states in the gap, whose unpaired electrons lie on the interstitial and the adjacent Ti 3d orbitals. The formation energy for the neutral O vacancy is 1.9 eV for the O-poor chemical potential, and similar to that of the neutral Ti interstitial, and has a lower formation energy for Ti interstitial under O-rich conditions. This indicates that both the O vacancy and Ti interstitial are relevant for oxygen deficiency in rutile TiO2 but the O vacancy will dominate under O-rich conditions. This resolves the questions about defect localisation and defect predominance in the literature.
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