A relationship between structural and electronic order-disorder effects and optical properties in crystalline TiO2 nanomaterials

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dc.contributor.authorSilva Júnior, E. [UNESP]
dc.contributor.authorLa Porta, F. A. [UNESP]
dc.contributor.authorLiu, M. S.
dc.contributor.authorAndres, J.
dc.contributor.authorVarela, J. A. [UNESP]
dc.contributor.authorLongo, Elson [UNESP]
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.contributor.institutionUniversidade de São Paulo (USP)
dc.contributor.institutionUniversitat Jaume I
dc.date.accessioned2015-10-22T06:17:19Z
dc.date.available2015-10-22T06:17:19Z
dc.date.issued2015-01-01
dc.description.abstractThe focus of this paper is on the analysis of the structural and electronic order-disorder effects at long, medium and short ranges of titanium dioxide (TiO2) nanoparticles synthesized by the sol-gel process followed by the microwave-assisted solvothermal (MAS) method at low temperatures and short reaction times. X-ray diffraction (XRD), Rietveld refinement, micro-Raman (MR) spectroscopy, transmission electron microscopy (TEM) and X-ray spectroscopy (EDX) were used to characterize the TiO2 nanoparticles. Optical properties were investigated by ultraviolet-visible (UV-vis) and photoluminescence (PL) measurements performed at room temperature. XRD and Rietveld refinement confirmed the presence of the anatase and brookite phases; nonetheless anatase is the major phase. The X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of only Ti4+ but the nonstoichiometry revealed that TiO2 NPs contain defects assigned to oxygen vacancies that lead to structural and electronic order-disorder effects observed by band gap narrowing and PL wide band emission. These intermediary energy levels (shallow and deep levels) created within the band gap act as acceptors/ donors of electrons and recombination centers. The oxygen vacancies (VOx, VO center dot and VO center dot center dot) responsible by degree of structural order-disorder are related to distortions (tilts) on the [TiO6] octahedron and changes in the bond lengths and bond angles between oxygen and titanium atoms that gave rise to new species of cluster makers such as [TiO6]', [TiO5 center dot V-O(x)], [TiO5 center dot VO center dot] and [TiO5 center dot VO center dot center dot]. This structural transformation is consistent with a redistribution of electron density from highly ordered [TiO6](x) clusters which form distorted [TiO6]'as well as complex [TiO5 center dot V-O(x)], [TiO5 center dot VO center dot] and [TiO5 center dot VO center dot center dot] clusters assigned to oxygen vacancies which were understood as displacements in the oxygen atoms'position in the bond lengths (Ti-O).en
dc.description.affiliationInstituto de Física de São Carlos, Universidade de São Paulo, P.O. Box 369, 13560-970 São Carlos, Brazil
dc.description.affiliationDepartment of Physical and Analytical Chemistry, Universitat Jaume I, Castelló de la Plana, Spain
dc.description.affiliationUnespUniversidade Estadual Paulista, LIEC, Instituto de Química, P.O. Box 355, CEP 14801-907 Araraquara, Brazil
dc.description.sponsorshipFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.description.sponsorshipCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
dc.description.sponsorshipConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.description.sponsorshipIdFAPESP: 2013/07296-2
dc.description.sponsorshipIdCNPq: 573636/2008-7
dc.description.sponsorshipIdCNPq: Prometeo/2009/053
dc.format.extent3159-3175
dc.identifierhttp://pubs.rsc.org/en/Content/ArticleLanding/2015/DT/C4DT03254C#!divAbstract
dc.identifier.citationDalton Transactions. Cambridge: Royal Soc Chemistry, v. 44, n. 7, p. 3159-3175, 2015.
dc.identifier.doi10.1039/c4dt03254c
dc.identifier.issn1477-9226
dc.identifier.urihttp://hdl.handle.net/11449/129619
dc.identifier.wosWOS:000349403100028
dc.language.isoeng
dc.publisherRoyal Soc Chemistry
dc.relation.ispartofDalton Transactions
dc.relation.ispartofjcr4.099
dc.relation.ispartofsjr1,306
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.titleA relationship between structural and electronic order-disorder effects and optical properties in crystalline TiO2 nanomaterialsen
dc.typeArtigo
dcterms.rightsHolderRoyal Soc Chemistry
unesp.campusUniversidade Estadual Paulista (Unesp), Instituto de Química, Araraquarapt

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Artigos - Físico Química - IQ
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