Theoretical Study of the Interstitial Oxygen Atom in Anatase and Rutile TiO2: Electron Trapping and Elongation of the r(O-O) Bond
Theoretical Study of the Interstitial Oxygen Atom in Anatase and Rutile TiO2: Electron Trapping and Elongation of the r(O-O) Bond
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DOI：
10.1021/jp110648q
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发表时间：
2011-04-28
影响因子：
3.7
通讯作者：
Yamashita, Koichi
中科院分区：
文献类型：
--
作者：
Kamisaka, Hideyuki;Yamashita, Koichi
采用基于密度泛函理论的第一性原理能带结构方法研究了TiO 2中的间隙氧原子（O-i）.两种多晶型的TiO 2，金红石和金红石结构，被认为是。在金红石中得到了对称的O-O结构，与文献报道的金红石中的结构非常相似。在两种多晶型物中，O-i将电子从导带捕获到O-O结构的σ * 轨道。键长r（O-O）在此过程中被拉长。还考察了O-i与Nb、Ta杂质之间的相互作用。两种杂质的吸引力都很弱。进行简单的统计分析以评估在O-i形成的情况。从目前的结果中得出两个结论。1)在富氧条件下，O-1以金红石或金红石结构形成于n型TiO 2中。2)熵因子来源于O-i的分布和导带中的电子，对室温下的自由能贡献很小。统计分析和实验O-2气体退火过程之间的差异意味着O-1的吸收和迁移的动力学的重要性。本文简要讨论了Nb掺杂TiO_2中O_2和Nb/Ta杂质的局域性。
Interstitial oxygen atoms (O-i) in TiO2 were investigated using the density functional theory-based first-principle band structure method. Two polymorphs of TiO2, anatase and rutile structures, were considered. A symmetric O-O) structure was obtained in rutile and is quite similar to the reported structure in anatase. In both polymorphs, O-i, traps electrons from the conduction band to the sigma* orbital of the O-O structure. The bond length r(O-O) is elongated in this process. The interactions between O-i and Nb or Ta impurities were also surveyed. There was weak attraction for both impurities. A simple statistical analysis was conducted to evaluate the O-i formation in anatase. Two conclusions were drawn from the present results. 1) O-i forms in n-type TiO2 in either the anatase or rutile structure under an O-rich condition. 2) The entropy factor, which originates from the distribution of O-i and from the electrons in the conduction band, makes a small contribution to the free energy at room temperature. The discrepancy between the statistical analysis and the experimental O-2 gas annealing process implies the importance of the kinetics of the absorption and migration of O-i. The locality of O-i and Nb/Ta impurities in Nb-doped anatase TiO2 is briefly discussed.