DFT-Based Theoretical Calculations of Nb- and W-Doped Anatase TiO2: Complex Formation between W Dopants and Oxygen Vacancies

• Published in: Journal of physical chemistry. C Vol. 114; no. 29; pp. 12777 - 12783
• Main Authors: Kamisaka, Hideyuki, Suenaga, Takahiro, Nakamura, Hisao, Yamashita, Koichi
• Format: Journal Article
• Language: English
• Published: American Chemical Society 29.07.2010
• Subjects: C: Electron Transport, Optical and Electronic Devices, Hard Matter
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp104355q

The structure and electronic states in Nb-doped TiO2 (TNO) and W-doped TiO2 (TWO) having the anatase phase were investigated using a first-principles DFT-based band structure method. In addition to the cases where the dopant substituted for a Ti atom, cells containing a dopant (MTi, where M = Nb and W) and an oxygen vacancy (VO) were calculated to clarify the role of oxygen vacancies in the system. Furthermore, cells containing two dopants and an oxygen vacancy (2MTi−VO) and cells with a dopant and two oxygen vacancies (MTi−2VO) were calculated. Energetically stable structures were found in the 2WTi−VO and WTi−2VO cells sampled, whereas the corresponding structures in TNO did not show any significant energy stabilization. Impurity states were found in the stable 2WTi−VO and WTi−2VO structures, and an approach of the two WTi atoms was found in 2WTi−VO. These findings suggest the possible formation of complex structures consisting of WTi dopants and oxygen vacancies. Our results are consistent with recent experiments on TWO by Takeuchi et al., and they rationalize the lower electronic conductivity of TWO versus TNO.