Intensities of 4f-4f transitions in glass materials

Malta, O.L.; Carlos, Luı́s D.

doi:10.1590/s0100-40422003000600018

Cited by 100 publications

(75 citation statements)

References 26 publications

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“…This can be explained by considering the dynamic coupling mechanism for 4f-4f transitions. 34 This mechanism is related to the occurrence of local transient electric dipoles, which are induced by the incident radiation on the electrons of the ligands, and these induced fields around the lanthanoid ions can explain the intensification of some hypersensitive 4f-4f transitions. The interaction between these induced dipoles and the metal transition quadrupole moment results in non-zero transition moments in such cases.…”

Section: Methodsmentioning

confidence: 99%

Effect of the vanadium(v) concentration on the spectroscopic properties of nanosized europium-doped yttrium phosphates

2012

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Nanosized rare earth phosphovanadate phosphors (Y(P,V)O 4 :Eu 3+ ) have been prepared by applying the organic-inorganic polymeric precursors methodology. Luminescent powders with tetragonal structure and different vanadate concentrations (0%, 1%, 5%, 10%, 20%, 50%, and 100%, with regard to the phosphate content) were then obtained for evaluation of their structural and spectroscopic properties. The solids were characterized by scanning electron microscopy, X-ray diffractometry, vibrational spectroscopy (Raman and infrared), and electronic spectroscopy (emission, excitation, luminescence lifetimes, chromaticity, quantum efficiencies, and Judd-Ofelt intensity parameters). The solids exhibited very intense 5 D 0 → 7 F J Eu 3+ transitions, and it was possible to control the luminescent characteristics, such as excitation maximum, lifetime and emission colour, through the vanadium(V) concentration. The observed luminescent properties correlated to the characteristics of the chemical environments around the Eu 3+ ions with respect to the composition of the phosphovanadates. The Eu 3+ luminescence spectroscopy results indicated that the presence of larger vanadium(V) amounts in the phosphate host lattice led to more covalent and polarizable chemical environments. So, besides allowing for control of the luminescent properties of the solids, the variation in the vanadate concentration in the obtained YPO 4 :Eu 3+ phosphors enabled the establishment of a strict correlation between the observable spectroscopic features and the chemical characteristics of the powders.

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Section: Methodsmentioning

confidence: 99%

Effect of the vanadium(v) concentration on the spectroscopic properties of nanosized europium-doped yttrium phosphates

2012

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“…[10,[154][155][156][157] The experimental oscillator strength P EXP , which is the quantity used to evaluate absorption bands, is directly proportional to the area under the absorption curve, and is given by: [158] …”

Section: Intensity Parameters Radiative and Nonradiative Transition mentioning

confidence: 99%

Lanthanide‐Containing Light‐Emitting Organic–Inorganic Hybrids: A Bet on the Future

et al. 2009

Self Cite

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Interest in lanthanide-containing organic-inorganic hybrids has grown considerably during the last decade, with the concomitant fabrication of materials with tunable attributes offering modulated properties. The potential of these materials relies on exploiting the synergy between the intrinsic characteristics of sol-gel derived hosts (highly controlled purity, versatile shaping and patterning, excellent optical quality, easy control of the refractive index, photosensitivity, encapsulation of large amounts of isolated emitting centers protected by the host) and the luminescence features of trivalent lanthanide ions (high luminescence quantum yield, narrow bandwidth, long-lived emission, large Stokes shifts, ligand-dependent luminescence sensitization). Promising applications may be envisaged, such as light-emitting devices, active waveguides in the visible and near-IR spectral regions, active coatings, and bio-medical actuators and sensors, opening up exciting directions in materials science and related technologies with significant implications in the integration, miniaturization, and multifunctionalization of devices. This review provides an overview of the latest advances in Ln(3+)-containing siloxane-based hybrids, with emphasis on the different possible synthetic strategies, photoluminescence features, empirical determination.

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“…In principle, electric dipoles are Laporte forbidden. However, provided that the site occupied by the Eu 3+ does not present a centre of inversion, an odd parity term relaxes the rule in the ligand field Hamiltonian making the transition, 5 D 0 → 7 F 0 , permitted [15,16]. Figure 4(a) contains the emission spectra of sol-gel glasses containing 0.5 mol% Eu 3+ and varying Mg : Eu mole ratios annealed for 2 h at 600…”

Section: Resultsmentioning

confidence: 99%

Luminescence Properties of Eu- and Mg-Codoped Sol-Gel SiO2 Glasses

Onani

Mushonga

Koao

et al. 2012

ISRN Nanotechnology

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A series of SiO 2 nanostructures codoped with Eu 3+ ; Mg 2+ ions were obtained by a sol-gel method. The gels synthesized by the hydrolysis of Si(OC 2 H 5 ) 4 , Eu(NO 3 ) 3 ·6H 2 O, and Mg(NO 3 ) 2 were heated in air at 600• C for 2 hours. Firstly, the total amount of Eu 3+ ions was varied from 0 to 2.0 mol% to investigate the effect of self-damping, while in the second case, the Eu 3+ ions were kept constant in the experiment at 0.5 mol% total doping and Mg 2+ ions varied. The samples were characterized by X-ray diffraction, TEM, EDS, and UV lamp-excited luminescence spectroscopy. The Eu 3+ ions were homogeneously dispersed in the silica and interacting with the small (1-5 nm) amorphous silica matrix. Strong red emissions located at 614 nm and 590 nm for doped and codoped SiO 2 were observed from the UV light excitation at room temperature. The composition of around 1.25 mol% Eu 3+ gave highest emission intensity. SiO 2 ; Mg 2+ ions portray strongly enhanced emissions due to energy transfer from Mg 2+ to Eu 3+ , which is due to radiative recombination. An increase in luminescence intensity was observed as the Mg 2+ -to-Eu 3+ ratio increased for the range investigated. The results show Eu 3+ ion is located inside or at the surface of disordered SiO 2 nanoparticles.

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Intensities of 4f-4f transitions in glass materials

Cited by 100 publications

References 26 publications

Effect of the vanadium(v) concentration on the spectroscopic properties of nanosized europium-doped yttrium phosphates

Effect of the vanadium(v) concentration on the spectroscopic properties of nanosized europium-doped yttrium phosphates

Lanthanide‐Containing Light‐Emitting Organic–Inorganic Hybrids: A Bet on the Future

Luminescence Properties of Eu- and Mg-Codoped Sol-Gel SiO2 Glasses

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