Charge compensation in trivalent cation doped bulk rutile TiO2

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dc.contributor.authorIwaszuk, Anna
dc.contributor.authorNolan, Michael
dc.contributor.funderScience Foundation Irelanden
dc.date.accessioned2017-12-18T15:49:15Z
dc.date.available2017-12-18T15:49:15Z
dc.date.issued2011-08-02
dc.date.updated2017-12-18T15:40:40Z
dc.description.abstractDoping of TiO2 is a very active field, with a particularly large effort expended using density functional theory (DFT) to model doped TiO2; this interest has arisen from the potential for doping to be used in tuning the band gap of TiO2 for photocatalytic applications. Doping is also of importance for modifying the reactivity of an oxide. Finally, dopants can also be unintentionally incorporated into an oxide during processing, giving unexpected electronic properties. To unravel properly how doping impacts on the properties of a metal oxide requires a modelling approach that can describe such systems consistently. Unfortunately, DFT, as used in the majority of studies, is not suitable for application here and in many cases cannot even yield a qualitatively consistent description. In this paper we investigate the doping of bulk rutile TiO2 with trivalent cations, Al, Ga and In, using DFT, DFT corrected for on-site Coulomb interactions (DFT + U, with U on oxygen 2p states) and hybrid DFT (the screened exchange HSE06 exchange correlation functional) in an effort to better understand the performance of DFT in describing such fundamental doping scenarios and to analyse the process of charge compensation with these dopants. With all dopants, DFT delocalizes the oxygen hole polaron that results from substitution of Ti with the lower valence cation. DFT also finds an undistorted geometry and does not produce the characteristic polaron state in the band gap. DFT + U and hybrid DFT both localize the polaron, and this is accompanied by a distortion to the structure around the oxygen hole site. DFT + U and HSE06 both give a polaron state in the band gap. The band gap underestimation present in DFT + U means that the offset of the gap state from both the valence and the conduction band cannot be properly described, while the hybrid DFT offsets should be correct. We have investigated dopant charge compensation by formation of oxygen vacancies. Due to the large number of calculations required, we use DFT + U for these studies. We find that the most stable oxygen vacancy site has either a very small positive formation energy or is negative, so under typical experimental conditions, anion vacancy formation will compensate for the dopant.en
dc.description.sponsorshipScience Foundation Ireland and Higher Education Authority (Irish Centre for High End Computing)en
dc.description.statusPeer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationIwaszuk, A. and Nolan, M. (2011) 'Charge compensation in trivalent cation doped bulk rutile TiO 2', Journal of Physics: Condensed Matter, 23(33), 334207 (11pp). doi: 10.1088/0953-8984/23/33/334207en
dc.identifier.doi10.1088/0953-8984/23/33/334207
dc.identifier.endpage334207-11en
dc.identifier.issn0953-8984
dc.identifier.journaltitleJournal of Physics: Condensed Matteren
dc.identifier.startpage334207-1en
dc.identifier.urihttps://hdl.handle.net/10468/5190
dc.identifier.volume23en
dc.language.isoenen
dc.publisherIOP Publishingen
dc.relation.projectinfo:eu-repo/grantAgreement/SFI/SFI Starting Investigator Research Grant (SIRG)/09/SIRG/I1620/IE/EMOIN: Engineering Metal Oxide Interfaces For Renewable Energy Photocatalysis/en
dc.rights© 2011 IOP Publishing Ltd. This is an author-created, un-copyedited version of an article accepted for publication in Journal of Physics: Condensed Matter. The publisher is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://stacks.iop.org/0953-8984/23/i=33/a=334207en
dc.subjectAugmented-wave methoden
dc.subjectPhotocatalytic activityen
dc.subjectElectronic structureen
dc.subjectOxygen vacanciesen
dc.subjectAnatase TiO2en
dc.subjectAb-initioen
dc.subjectSurfaceen
dc.subjectAbsorptionen
dc.subjectDensity functional theoryen
dc.subjectActive fielden
dc.subjectAnion vacancyen
dc.subjectCharge compensationen
dc.subjectDoped-TiOen
dc.subjectExchange-correlation functionalsen
dc.subjectExperimental conditionsen
dc.subjectFormation energiesen
dc.subjectGap stateen
dc.subjectHole polaronsen
dc.subjectHybrid DFTen
dc.subjectMetal oxidesen
dc.subjectPhotocatalytic applicationen
dc.subjectRutile TiOen
dc.subjectTiOen
dc.subjectTrivalent cationsen
dc.subjectValence cationsen
dc.subjectDoping (additives)en
dc.subjectElectron mobilityen
dc.subjectElectronic propertiesen
dc.subjectEnergy gapen
dc.subjectGalliumen
dc.subjectMetallic compoundsen
dc.subjectOxide mineralsen
dc.subjectOxygenen
dc.subjectPolaronsen
dc.subjectPositive ionsen
dc.subjectTitanium dioxideen
dc.titleCharge compensation in trivalent cation doped bulk rutile TiO2en
dc.typeArticle (peer-reviewed)en
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