Fotoluminescência em materiais com desordem estrutural

Lucena, Poty Rodrigues de; Pinheiro, C. D.; Longo, Elson; Pizani, P. S.; Lázaro, Sérgio Ricardo de; Souza, A. G.; Santos, I. M. G.

doi:10.1590/s0366-69132004000200011

Cited by 20 publications

(22 citation statements)

References 14 publications

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“…This is a strong indication that the disordered phase (amorphous phase) is responsible for photoluminescence. 20 As the calcination temperature increases, the order begins to increase in the medium and long range, so the electron-hole transitions suffer a decrease, thus decreasing the intensity of the photoluminescent signal, and as a consequence a high photocatalytic activity.…”

Section: Resultsmentioning

confidence: 99%

Influence of the Number of Layers and Crystallization Temperature on the Photocatalytic Activity of Tio2 / In2O3 Thin Films

Garcia¹,

Gurgel²,

Lovisa³

et al. 2017

MSEIJ

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The resin was prepared by the method of polymerization of complex, this method uses in situ polymerization, soluble metal polymerisation compounds are prepared with citric acid, and only AbstractThe TiO 2 /In 2 O 3 thin films were prepared by the spin coating method, varying their number of layers (4, 8 and 16 layers). The Method of polymerization of complex (CPM) was used to synthesize the precursor resins in order to produce thin films. The TiO 2 /In 2 O 3 films were heat-treated at 300°C, 500°C and 700°C and characterized by X-ray diffraction, scanning electron microscopy (FEG-SEM), atomic force microscopy (AFM), UV-vis spectrophotometer and photoluminescence (PL). It was found that the band gap energy of the as-prepared TiO 2 /In 2 O 3 composite thin films decrease as temperature increases. According to the UV-vis diffuse reflectance spectra, the TiO 2 /In 2 O 3 composite shows good visible-light absorption ability. The photoluminescent properties of the films were studied at room temperature using a wavelength of 350nm excitation. High photoluminescent intensity was observed for the films treated at 300°C heat, studied in different films. The photocatalytic activity of the composite TiO 2 /In 2 O 3 was evaluated by the photodecomposition of methylene blue dye in aqueous solution and showed that all the composite samples presented excellent photocatalytic performance even when recycled. This study shows that the coupling of TiO 2 with In 2 O 3 is an effective way to increase the TiO 2 absorption in the visible region for catalytic applications and that the temperature has a greater influence on the results than the number of layers.

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Section: Resultsmentioning

confidence: 99%

Influence of the Number of Layers and Crystallization Temperature on the Photocatalytic Activity of Tio2 / In2O3 Thin Films

Garcia¹,

Gurgel²,

Lovisa³

et al. 2017

MSEIJ

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“…As can be seen from the analysis of the diffraction patterns and identification of the formed crystalline phases, the powder sample as cast, without heat treatment (a), has structure composed by crystalline phases identified as lithium titanium silicate (Li 2 reported in the literature indicate that there may be a suitable quantitative relation between the formed crystalline and amorphous phases which is related to a better photoluminescence of the produced materials [2,[10][11][12]. Thus, one can say that even the composition (a) LTS (without thermal treatment) shows potential to demonstrate the photoluminescence phenomena.…”

Section: Resultsmentioning

confidence: 99%

“…This emission that is related to the structural disorder (atomic and/or molecular) induces the formation of different energy states in the gap between the valence band and the conduction band, facilitating the transition of electrons [2]. Thus, the photoinduced properties are determined by the level of interactions between electromagnetic radiation and the electrons of the atoms in the material [3].…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of Li2TiSiO5 obtained by melting and solid-state reaction

Souza

Cesconeto

Arcaro

et al. 2016

J Therm Anal Calorim

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In this work, the synthesis of the Li 2 TiSiO 5 photoluminescent compound, obtained from a stoichiometric mixture of Li 2 CO 3 , SiO 2 and TiO 2 nanoparticles, was investigated by two different routes named route I (melting and quenching) and route II (solid-state reaction). In the route I, the raw materials were melted (1550°C/2 h) and cooled into water. Subsequently, the solidified product was milled (30 min) in a high-energy mill. In the route II, the raw materials were directly milled (10 min). The obtained powders, from both routes, were heat treated at different temperatures (900-1000°C/60 min) and then subjected to crystallographic (XRD) and thermal (DSC) analyses in order to investigate the resulting structure and the associated physical-chemical reactions. The results showed that it is possible to obtain the Li 2 TiSiO 5 compound from both synthesis routes but, apparently, the route I seems to be more appropriated to obtain the Li 2 TiSiO 5 compound and to demonstrate the photoluminescence phenomena with and even without thermal treatment.

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“…In the inverse spinels, on the other hand, the A 2+ ions and half the B 3+ ions are in octahedral holes, and the remaining B 3+ ions are in tetrahedral holes [9][10][11][12] In fact, very few spinels have exactly the normal or inverse structure, and these are sometimes called mixed spinels. Li 2 ZnTi 3 O 8 presents a derived spinel structure with P4 3 32 space group, in which the octahedral 12d and 4b sites are occupied by Ti and Li respectively, and the tetrahedral 8c sites are shared by Zn and Li, suggesting an intermediary spinel structure [13][14][15] .…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic Properties of pigment Li2-xZn1-xPrxTi3O8

et al. 2016

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Inorganic compounds doped with rare earths (Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Eu 3+ , Gd 3+ , Tb 3+ , Tm 3+ ) have been used in various applications including light-emitting devices such as fluorescent lamps, cathode ray tubes, lasers and inorganic pigments. In this study, Pr 3+ is doped in spinel Li 2 ZnTi 3 O 8 system and synthesized by the polymeric precursor method, which is based on the process developed by the Pechini, and characterized by X-ray diffraction, UV-visible and CIE-L colorimetric measures * a * b *., in order to study the effect of doping and thermal treatment on its colorimetric properties. With three different samples of Pr 3+ doping (0.01; 0.05 and 0.1 mol%) were prepared and calcined at 500°C, 600°C, 700°C, 800°C and 900°C for 4 h. The analysis of X-ray diffraction confirmed the formation of pure phases with spinel structure and average crystallite size of less than 46 nm. It was found that the colorimetric properties ranging from green to red, in accordance with the increase in the concentration of Pr 3+ and thermal processing temperature.

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Fotoluminescência em materiais com desordem estrutural

Cited by 20 publications

References 14 publications

Influence of the Number of Layers and Crystallization Temperature on the Photocatalytic Activity of Tio2 / In2O3 Thin Films

Influence of the Number of Layers and Crystallization Temperature on the Photocatalytic Activity of Tio2 / In2O3 Thin Films

Synthesis and characterization of Li2TiSiO5 obtained by melting and solid-state reaction

Spectroscopic Properties of pigment Li2-xZn1-xPrxTi3O8

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