A relationship between structural and electronic order–disorder effects and optical properties in crystalline TiO2 nanomaterials
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Otros documentos de la autoría: Silva Junior, E.; La Porta, Felipe A.; Liu, M.S.; Andres, Juan; Varela, José A.; Longo, Elson
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Mostrar el registro completo del ítemcomunitat-uji-handle:10234/9
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http://dx.doi.org/10.1039/C4DT03254C |
Metadatos
Título
A relationship between structural and electronic order–disorder effects and optical properties in crystalline TiO2 nanomaterialsAutoría
Fecha de publicación
2015Editor
Royal Society of ChemistryISSN
1477-9226; 1477-9226Tipo de documento
info:eu-repo/semantics/articleVersión de la editorial
http://pubs.rsc.org/en/content/articlelanding/2015/dt/c4dt03254c#!divAbstractVersión
info:eu-repo/semantics/publishedVersionPalabras clave / Materias
Resumen
The 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 ... [+]
The 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˙ and VO˙˙) 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·VOx], [TiO5·VO˙] and [TiO5·VO˙˙]. 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·VOx], [TiO5·VO˙] and [TiO5·VO˙˙] clusters assigned to oxygen vacancies which were understood as displacements in the oxygen atoms’ position in the bond lengths (Ti–O). [-]
Publicado en
Dalton Transactions, 2015, vol. 44, núm. 7Derechos de acceso
This journal is © The Royal Society of Chemistry 2015
JUNIOR, E. Silva, et al. A relationship between structural and electronic order–disorder effects and optical properties in crystalline TiO 2 nanomaterials. Dalton Transactions, 2015, vol. 44, no 7, p. 3159-3175. <http://dx.doi.org/10.1039/C4DT03254C>
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