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First-principles Study of Point Defects in Anatase TiO2

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Author(s): FENG Qing

Journal: Journal of Chongqing Normal University
ISSN 1672-6693

Volume: 26;
Issue: 1;
Start page: 78;
Date: 2009;
Original page

Keywords: anatase | TiO2 | point defects | first-principle theory

ABSTRACT
Recently the way of reducing the TiO2 hand gap to enhance the activity of TiO2has widely been investigated. In this paper the property of point defects in anatase TiO2 is investigated and the character of hand structure and density of states is analyzed by using first-principle pseudopotential calculations based on density-functional theory (DFT). It is discovered that the crystal structure was changed due to pulling into vacancy; the nearby oxygen atom has the trend of closing to the oxygen vacancy and keeping off the titanium vacancy, whereas the nearby titanium atom has the trend of closing to the titanium vacancy and keeping off the oxygen vacancy. Oxygen vacancy makes Fermi energy rise about 2.6 eV and titanium vacancy makes Fermi energy go down. A defect level appeares in the gap about 0.25 eV above the top of valence hand due to titanium vacancy. Theoretical results show that oxygen vacancy causing conduction hand wider is n-type impurity and titanium vacancy causing conduction hand narrower is p-type impurity; the redundant electrons nearby oxygen vacancy contributed to valence band, which causes the change of the electric populations and alters the local motional property of electrons.

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