Surface and subsurface oxygen vacancies in anatase TiO2 and differences with rutile
Surface and subsurface oxygen vacancies in anatase TiO2 and differences with rutile
复制标题
DOI：
10.1103/physrevb.79.092101
复制
发表时间：
2009-03-01
影响因子：
3.7
通讯作者：
Selloni, Annabella
中科院分区：
文献类型：
--
作者：
Cheng, Hongzhi;Selloni, Annabella
采用第一性原理密度泛函理论在广义梯度近似下研究了金红石型TiO_2（101）和TiO_2（001）表面和亚表面氧空位的相对稳定性，并与典型金红石型TiO_2（110）表面进行了比较.我们的研究结果表明，这些缺陷是显着更稳定的亚表面比在表面网站的情况下，金红石型TiO 2（110），而桥氧网站有利于O空位。此外，O-空位扩散途径的计算表明，从表面到亚表面的位置扩散的能量势垒足够低，以确保在典型的表面退火温度下的空位分布的快速平衡。这些结果可以解释为什么，实验上，发现金红石表面具有显着较低的缺陷浓度和/或更难以减少比金红石。
First-principles density-functional theory calculations in the generalized gradient approximation are carried out to study the relative stabilities of oxygen vacancies at surface and subsurface sites of anatase TiO2(101) and TiO2(001), and, for comparison, of the prototypical rutile TiO2(110) surface. Our results indicate that these defects are significantly more stable at subsurface than at surface sites in the case of anatase surfaces, whereas bridging oxygen sites are favored for O vacancies at rutile TiO2(110). Also, calculations of O-vacancy diffusion pathways at anatase TiO2(101) show that the energy barrier to diffuse from surface-to-subsurface sites is sufficiently low to ensure a rapid equilibration of the vacancy distribution at typical surface annealing temperatures. These results could explain why, experimentally, anatase surfaces are found to have a significantly lower defect concentration and/or to be more difficult to reduce than those of rutile.