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铁道科学与工程学报

JOURNAL OF RAILWAY SCIENCE AND ENGINEERING

Vol. 17    Special 1    November 2007

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An accurate theoretical study on intrinsic defect energetics in rutile TiO2
MA Xin-guo(马新国), JIANG Jian-jun(江建军), LIANG Pei(梁  培), WANG Juan(王  娟)

Department of Electronic Science and Technology, Huazhong University of Science and Technology,
Wuhan 430074, China

Abstract:An accurate theoretical study on the intrinsic point defects in rutile TiO2 was carried out by first-principles calculations using plane-wave pseudopotential method. The structural parameters of defect-free bulk rutile TiO2 were calculated, which are close to experimental data. And the effects of point defects on the geometry structures were analyzed. To get accurate value of formation energy and charge transfer levels, several technical details must be considered, such as the position of EVBM originating from supercell size and electrostatic interactions between the charged defects, and band-gap error etc. The formation energies of the point defects in various charge states were given as a function of Fermi level for the two limiting values of extreme O-rich conditions and extreme Ti-rich conditions. Under extreme Ti-rich conditions, Ti4+ interstitial and VO2+ have very low formation energy, and wound thus exist in significant quantities, namely, producing the intrinsic n-type TiO2. The stability of these point defects is traced back to the multivalence of titanium. Under extreme reducing condition, Frenkel defect comprised of Tii4+ and VTi4- would be formed in TiO2.

 

Key words: first-principles; TiO2; point defect; formation energy

ISSN 1672-7029
CN 43-1423/U

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