<i>Ab initio</i>study of oxygen vacancies in BaTiO<sub>3</sub>

Donnerberg, H.; Birkholz, Adam B.

doi:10.1088/0953-8984/12/38/301

Cited by 47 publications

(48 citation statements)

References 24 publications

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“…24 In SrTiO 3 the singlet ground state is the result of the coupling of the two electrons which occupy 3d(z 2 ) levels on the two Ti atoms. The charge distribution is similar to that found for the same kind of defect in other perovskites like PbTiO 3 , 10 BaTiO 3 , 11 and KNbO 3 .…”

supporting

confidence: 85%

“…6,9,10,11 In this paper we have considered for the first time the competition between magnetic and non-magnetic coupling of the two extra electrons associated with the vacancy. In order to do this, various methods and computational approaches have been adopted.…”

Section: Discussionmentioning

confidence: 99%

“…6,10,11,13 However, there are some aspects of the nature of point defects, in particular related to their magnetic behavior, that are difficult to treat at the DFT level. 18 -20 One recent and illustrative example is that of the spin localization in an Al substitutional impurity in SiO 2 .…”

Section: Introductionmentioning

confidence: 99%

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Electronic structure of a neutral oxygen vacancy inSrTiO3

et al. 2003

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The electronic structure of an isolated oxygen vacancy in SrTiO 3 has been investigated with a variety of ab initio quantum mechanical approaches. In particular we compared pure density functional theory ͑DFT͒ approaches with the Hartree-Fock method, and with hybrid methods where the exchange term is treated in a mixed way. Both local cluster models and periodic calculations with large supercells containing up to 80 atoms have been performed. Both diamagnetic ͑singlet state͒ and paramagnetic ͑triplet state͒ solutions have been considered. We found that the formation of an O vacancy is accompanied by the transfer of two electrons to the 3d(z 2 ) orbitals of the two Ti atoms along the Ti-Vac-Ti axis. The two electrons are spin coupled and the ground state is diamagnetic. New states associated with the defect center appear in the gap just below the conduction band edge. The formation energy computed with respect to an isolated oxygen atom in the triplet state is 9.4 eV.

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confidence: 85%

Section: Discussionmentioning

confidence: 99%

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Electronic structure of a neutral oxygen vacancy inSrTiO3

et al. 2003

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“…Theoretical studies reveal that the ground state of the singly ionized oxygen vacancy, V · o , involves a transfer of electron density to the 3d 3z 2 −r 2 orbital of the two neighbor axial Ti ions. 56,57 Clustering of the two oxygen vacancies in the form of the axial [V ·· o -Ti 2+ -V ·· o ] ·· complex defect with 2 electrons localized on the Ti 3d 3z 2 −r 2 orbital forming an in-gap electronic state at 0.6 eV below conduction band minimum has been predicted by Cuong et al 58 In a relevant study on Nb-doped SrTiO 3 , Mechelen et al have attributed MIR absorption to the multiphonon sidebands due to the incoherent electron-phonon coupling. 25 They found that the missing Drude spectral weight is nearly recovered in the MIR range.…”

Section: B Mid Infrared Bandmentioning

confidence: 99%

Doping and temperature-dependent optical properties of oxygen-reducedBaTiO3−δ

et al. 2010

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We report on optical properties of reduced BaTiO 3−δ at different doping levels including insulating and metallic samples. In all the samples, including metallic one, we observe structural phase transitions from the changes of the infrared active phonon modes. Metallic ground state is confirmed by the Drude-type low-frequency optical reflectance. Similar to SrTiO 3−δ we find that the mid-infrared absorption band in BaTiO 3−δ appears and grows with an increase in the oxygen vacancy concentration. Upon decrease in temperature from 300 K, the mid-infrared band shifts slightly to higher frequency and evolves into two bands: the existing band and a new and smaller band at lower frequency. The appearance of the new and smaller band seems to be correlated with the structural phase transitions.

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“…On the other hand, several authors reported that the EPR peak with g ≈ 1.97 may be caused by intrinsic Ti 3+ related defects in BaTiO 3 [16][17][18][19][20][21][22][23][24] . A few of them observed this peak just in reduced BaTiO 3 ceramic [20,25]. Some authors whose examinations included EPR spectra at room temperature and above, attributed a peak at g = 1.97 to the localized Ti 3+ states [16].…”

Section: Resultsmentioning

confidence: 99%