Near-infrared photoluminescence in titania: Evidence for phonon-replica effect

Montoncello, F.; Carotta, M.C.; Cavicchi, B.T.; Ferroni, Matteo; Giberti, A; Guidi, V.; Malagù, C.; Martinelli, G.; Meinardi, F.

doi:10.1063/1.1586961

Cited by 85 publications

(47 citation statements)

References 29 publications

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“…But this sole effect is insufficient for enhancing the intense visible PL at room temperature, as can be seen in the more disordered sample ͑treated at 200°C͒ which presents a smaller PL intensity than the other order-disordered samples ͑treated at 300 and 400°C͒. The experimental gap energies of the PWO thin films containing structural order-disorder are higher than the excitation energy used for collecting the PL spectra ͑2.54 eV, 488 nm͒; such observation confirms the fact pointed out by Montoncello et al 66 that PL often highlights features that absorption measurements would rarely define as the properties of the energy levels lying within the band gap of a material.…”

Section: Photoluminescence Measurements and Interpretationsupporting

confidence: 77%

Contribution of structural order-disorder to the green photoluminescence ofPbWO4

et al. 2007

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An intense and broad visible photoluminescence ͑PL͒ band was observed at room temperature in structurally disordered PbWO 4 thin films. The scheelite lead tungstate ͑PbWO 4 ͒ films prepared by the polymeric precursor method and annealed at different temperatures were structurally characterized by means of x-ray diffraction and atomic force microscopy analysis. Quantum-mechanical calculations showed that the local disorder of the network modifier ͑Pb͒ has a very important role in the charge transfer involved in the green PL emission. The experimental and theoretical results are in good agreement, both indicating that the generation of the intense visible PL band is related to simultaneous structural order and disorder in the scheelite PbWO 4 lattice.

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Section: Photoluminescence Measurements and Interpretationsupporting

confidence: 77%

Contribution of structural order-disorder to the green photoluminescence ofPbWO4

et al. 2007

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“…13,14 Moreover, the PL spectrum of TiO 2 is strongly dependent on the surface condition, and hence information on surface properties can be obtained by PL spectroscopy. 15 To the best of our knowledge, few attention has been paid to optical properties of TONT, especially for the well-organized array formed directly on titanium substrates.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and photoluminiscent properties of titanium oxide nanotube arrays

Dong¹,

Huang²,

Li³

et al. 2008

J. Braz. Chem. Soc.

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Um arranjo de nanotubos de óxido de titânio alinhados verticalmente foi gerado com sucesso na superfície de um substrato de titânio pela técnica de anodização. Os nanotubos foram caracterizados por microscopia eletrônica de varredura (MEV), difratometria de raios X de pó (DRX), espectroscopia Raman e espectroscopia de fotoluminescência. Os resultados indicam que o tamanho dos nanotubos de óxido de titânio é altamente dependente da voltagem aplicada e que suas propriedades de fotoluminescência são fortemente influenciadas pela estrutura cristalina. Adicionalmente, efeitos quânticos de tamanho estão presentes nas propriedades dos nanotubos de TiO 2 .An array of vertically aligned titanium oxide nanotubes was successfully grown on the surface of a titanium substrate by the anodization technique. The nanotubes were characterized by scanning electron microscopy (SEM), powder X-ray diffractometry (XRD), Raman spectroscopy and photoluminescence spectroscopy (PL). The results indicate that the size of the titanium oxide nanotube is greatly dependent on the applied voltage, and its photoluminescence properties are strongly influenced by the crystal structure. In addition, it is shown that quantum size effects are present in the optical properties of TiO 2 nanotubes. Keywords: oxides, chemical synthesis, crystal structure, photoluminescent IntroductionIn recent years, titanium oxide (TiO 2 ) has received much attention from researchers owing to its properties including photocatalytic activity. Anatase and rutile are the two main crystalline structures of TiO 2 , with band gap energies at 3.2 and 3.0 eV, respectively. 1 The photocatalytic activity of TiO 2 depends on its surface to volume ratio and crystal structure, and several studies have been performed in order to investigate these issues. 2,3 In particular, one dimensional TiO 2 such as nanotubes is more attractive because of its large specific surface area, which has more reactive sites to absorb and oxidize pollutants such as benzene, phenol, and p-chlorophenol. 4 To produce one dimensional TiO 2 , a number of methods have been used, such as hydrothermal 5 and anodic alumina membranes (AAM) methods, 6 chemical vapor deposition, 7 and anodic oxidation. 8 Among these methods, the anodic oxidation is shown to be a powerful and efficient technique. Gong has fabricated the first generation of titania nanotube array by anodization using an aqueous HF-based electrolyte, and TiO 2 nanotube (TONT) arrays could be grown up to a length of 500 nm. 9 The results from Schmuki indicate that the TONT array length can be increased up to 7 µm when the pH of the anodization electrolyte is kept high while remaining acidic. 10 In 2006, Grimes reported a new generation of vertically oriented TiO 2 nanotubes with length up to 134 µm by using various non-aqueous electrolytes. 11 In our previous work, a TONT array was grown on the surface of a titanium substrate by the anodization technique. 12 The properties of this TONT array are investigated further in this work.The photoluminescence (PL...

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“…It has been reported that the visible emission from TiO 2 is related to the oxygen vacancies in the anatase phase, while the NIR emission is pertaining to the Ti 3+ ions in the rutile phase. [11][12][13]20 In our previous work, it was found that if the TiO 2 film prepared by sputtering consisted of both anatase and rutile phases, almost no EL could be detected from the TiO 2 /p + -Si heterostructured device. 21 However, in this work both the visible and NIR emissions occur in the TiO 2 /p + -Si heterostructured device with the TiO 2 film derived from the etched Ti film, which is composed of anatase and rutile phases.…”

Section: Methodsmentioning

confidence: 99%

“…10,11 However, the previous reports primarily concern the cathodoluminescence and photoluminescence of rutile TiO 2 . 12,13 The EL from the device based on the rutile TiO 2 , which is of technological significance, has not been realized to date. For the formation of rutile TiO 2 at low temperatures, etching of titanium (Ti) in combination with subsequent oxidation has been proved to be a feasible strategy.…”

Section: Introductionmentioning

confidence: 99%

Visible and near-infrared electroluminescence from TiO2/p+-Si heterostructured device

et al. 2014

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We report on visible and near-infrared (NIR) electroluminescence (EL) from the device based on the TiO2/p+-Si heterostructure, in which the TiO2 film is composed of anatase and rutile phases. As the device is applied with sufficiently high forward bias with the positive voltage connecting to p+-Si, the visible EL peaking at ∼600 nm along with the NIR EL centered at ∼810 nm occur simultaneously. It is proposed that the oxygen vacancies in the anatase TiO2 and Ti3+ defect states in the rutile TiO2 are the responsible centers for the visible and NIR EL, respectively.

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Near-infrared photoluminescence in titania: Evidence for phonon-replica effect

Cited by 85 publications

References 29 publications

Contribution of structural order-disorder to the green photoluminescence ofPbWO4

Contribution of structural order-disorder to the green photoluminescence ofPbWO4

Fabrication and photoluminiscent properties of titanium oxide nanotube arrays

Visible and near-infrared electroluminescence from TiO2/p+-Si heterostructured device

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