Judd&amp;ndash;Ofelt Analysis of Eu&lt;sup&gt;3+&lt;/sup&gt; Emission in TiO&lt;sub&gt;2&lt;/sub&gt; Anatase Nanoparticles

Brik, M.G.; Antic, &Zcaron;eljka M.; Vuković, Katarina; Dramićanin, Miroslav

doi:10.2320/matertrans.ma201566

Cited by 34 publications

(12 citation statements)

References 27 publications

(20 reference statements)

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“…The systematic investigations clearly indicate that quantum yield can be quite well derived from the luminescence spectra of Eu 3+ . The ratio of the radiative transition probabilities A RAD of the 5 D 0 → 7 F J (where J = 2, 4) electric-dipole transitions and the 5 D 0 → 7 F 1 magnetic-dipole transition of Eu 3+ in terms of the ratio of areas S under corresponding luminescence bands can be estimated using the following Equation (2) [36]:ARAD(D50→F72,4)ARAD(D50→F71)=normalS(D50→F72,4)normalS(D50→F71)…”

Section: Resultsmentioning

confidence: 99%

Reddish-Orange Luminescence from BaF2:Eu3+ Fluoride Nanocrystals Dispersed in Sol-Gel Materials

et al. 2019

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Nanocrystalline transparent BaF2:Eu3+ glass-ceramic materials emitting reddish-orange light were fabricated using a low-temperature sol-gel method. Several experimental techniques were used to verify structural transformation from precursor xerogels to sol-gel glass-ceramic materials containing fluoride nanocrystals. Thermal degradation of xerogels was analyzed by thermogravimetric analysis (TG) and differential scanning calorimetry method (DSC). The presence of BaF2 nanocrystals dispersed in sol-gel materials was confirmed by the X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM). In order to detect structural changes in silica network during annealing process, the infrared spectroscopy (IR-ATR) was carried out. In particular, luminescence spectra of Eu3+ and their decays were examined in detail. Some spectroscopic parameters of Eu3+ ions in glass-ceramics containing BaF2 nanocrystals were determined and compared to the values obtained for precursor xerogels. It was observed, that the intensities of two main red and orange emission bands corresponding to the 5D0→7F2 electric-dipole transition (ED) and the 5D0→7F1 magnetic-dipole (MD) transition are changed significantly during transformation from xerogels to nanocrystalline BaF2:Eu3+ glass-ceramic materials. The luminescence decay analysis clearly indicates that the measured lifetime 5D0 (Eu3+) considerably enhanced in nanocrystalline BaF2:Eu3+ glass-ceramic materials compared to precursor xerogels. The evident changes in luminescence spectra and their decays suggest the successful migration of Eu3+ ions from amorphous silica network to low-phonon BaF2 nanocrystals.

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Section: Resultsmentioning

confidence: 99%

Reddish-Orange Luminescence from BaF2:Eu3+ Fluoride Nanocrystals Dispersed in Sol-Gel Materials

et al. 2019

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“…The Ω 2 parameter is sensitive to the local structure and composition of the host material and can be associated with the asymmetry and covalence of the rare-earth site [65,71,72], while Ω 4 parameter can be related to the viscosity and rigidity. If one use Ω 2 to assess the magnitude of covalence between Eu 3+ and surrounding ligands (the larger the Ω 2 , the stronger the covalence), it is possible to conclude that covalence increases with reduction of particles size.…”

Section: Judd-ofelt Analysismentioning

confidence: 99%

Particle size effects on the structure and emission of Eu3+:LaPO4 and EuPO4 phosphors

Gavrilović

Periša

Papan

et al. 2018

Journal of Luminescence

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This paper provides the detailed study of (nano)particle's size effect on structural and luminescent properties of LaPO 4 :Eu 3+ synthesized by four different methods: high temperature solid-state, co-precipitation, reverse micelle and colloidal. These methods delivered monoclinic monazite-phase submicron particles (> 100 nm), 4 × 20 nm nanorods and 5 nm spheres (depending on the annealing temperature), 2 × 15 nm nanorods, and ultrasmall spheres (2 nm), respectively. The analysis of emission intensity dependence on Eu 3+ concentration showed that quenching concentration increases with a decrease of the particle size. The critical distance for energy transfer between Eu 3+ ions is found to be 18.2 Å, and the dipole-dipole interaction is the dominant mechanism responsible for the concentration quenching of emission. With the increase in Eu 3+ concentration, the unit-cell parameter slightly increases to accommodate larger Eu 3+ ions at sites of smaller La 3+ ions. Photoluminescent emission spectra presented four characteristic bands in the red spectral region: at 592 nm (5 D 0 → 7 F 1), at 612 nm (5 D 0 → 7 F 2), at 652 nm (5 D 0 → 7 F 3) and at 684 nm (5 D 0 → 7 F 4), while in small colloidal nanoparticles additional emission bands from host defects appear at shorter wavelengths. Intensities of f-f electronic transitions change with particles size due to small changes in symmetry around europium sites, while emission bandwidths increase with the reduction of particle size due to increased structural disorder. Judd-Ofelt analysis showed that internal quantum yield of Eu 3+ emission is strongly influenced by particle's morphology.

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“…Knowledge of the phase of TiO2 becomes important for an accurate determination of the refractive index of the material. TiO2 can crystallize in three different phases[49,50], with each phase reported as having a different refractive index[51].Figure 2 (a)shows the collected Raman spectra for TiO2 IOs prepared from 500 nm (D500) and 350 nm (D350) diameter PS sphere opals. Each spectrum displays four distinct peaks at approximately 152, 401, 524 and 643 cm -1 , corresponding to the Eg, B1g, A1g…”

mentioning

confidence: 99%

“…However, for the TiO2 IO materials, the expected transmission dips for the FCC (111) plane are not observed. Anatase TiO2 (n = 2.49)[51] and air (n = 1) in an FCC geometry yield an effective refractive index of nIO = 1.53 giving a predicted (111) transmission dip of 959 nm for 383 nm TiO2 pore diameters and 699 nm for 279 nm TiO2 pore diameters. These predictions differ drastically from experimental observations for the corresponding IO structures, where transmission dips were observed at 703…”

mentioning

confidence: 99%

Tetrahedral framework of inverse opal photonic crystals defines the optical response and photonic band gap

Lonergan

McNulty

O’Dwyer

2018

Journal of Applied Physics

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By forming anatase TiO2 inverse opals by infiltration of an opal photonic crystal, we demonstrate that the optical response and angle-resolved blue-shift of the band-gap of the inverse opal structure is defined by a particular three-dimensional structure of the infilled voids. The optical structure of TiO2 inverse opals usually displays significant deviation from its physical structure and from theoretically predicted position of the photonic band-gap. Following rigorous structural characterization of the parent opal template and TiO2 inverse opals, alternative explanations for the signature of optical transmission through inverse opals is proposed. These approaches posit that, for light-matter interaction, an inverse opal is not precisely the inverse of an opal. Accurate parameters for the structure and material properties can be obtained by invoking a Bragg FCC selection rule-forbidden (-211) plane, which is not a realistic model for diffraction in the IO. Alternatively, by assuming optical interactions with just the periodic arrangement of tetrahedral filled interstitial sites in the structure of inverse opal, a complete reconciliation with spectral blue-shift with angle, photonic band gap and material parameters are obtained when a reduced unit cell is defined based on interstitial void filling. The analysis suggests a reduced interplanar spacing (d = 1/√3 D, for pore diameter D), based on the actual structure of an inverse opal in general, rather than a definition based on the inverse of an FCC packed opal. This approach provides an accurate and general description for predicting the spectral response and material parameters of ordered inverse opal photonic crystal materials.

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Judd–Ofelt Analysis of Eu<sup>3+</sup> Emission in TiO<sub>2</sub> Anatase Nanoparticles

Cited by 34 publications

References 27 publications

Reddish-Orange Luminescence from BaF2:Eu3+ Fluoride Nanocrystals Dispersed in Sol-Gel Materials

Reddish-Orange Luminescence from BaF2:Eu3+ Fluoride Nanocrystals Dispersed in Sol-Gel Materials

Particle size effects on the structure and emission of Eu3+:LaPO4 and EuPO4 phosphors

Tetrahedral framework of inverse opal photonic crystals defines the optical response and photonic band gap

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