scholarly journals Analysis of Eu3+Emission from Mg2TiO4Nanoparticles by Judd-Ofelt Theory

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Katarina Vuković ◽  
Mina Medić ◽  
Milica Sekulić ◽  
Miroslav D. Dramićanin
Keyword(s):  
Theoretical Analysis ◽  
Quantum Efficiency ◽  
Metal Ion ◽  
Emission Spectra ◽  
Electronic Transitions ◽  
Ofelt Theory ◽  
Intensity Parameters ◽  
Different Temperatures ◽  
High Asymmetry ◽  
The Eu

Eu3+doped Mg2TiO4(2 at% of Eu) nanoparticles which are 5 to 10 nm in diameter are prepared by Pechini-type polymerized complex route followed with the calcination in the temperature range from 400°C to 700°C. Emission spectra display characteristicD0→FJ  (J=0, 1, 2, 3, and 4) spin forbidden f-f electronic transitions of the Eu3+ions with the most pronounced emission coming fromD0→F2  transition and with the emission decays varying between 0.57 and 0.87 ms for samples prepared at different temperatures. Judd-Ofelt theoretical analysis of the emission spectra of Eu3+ions was performed, which allowed calculating radiative and nonradiative emission probabilities, Judd-Ofelt intensity parameters, and the quantum efficiency of the Eu3+emission in the Mg2TiO4nanoparticles. The analyses showed the existence of high asymmetry around the metal ion sites. Also, the largest quantum efficiency of emission of 58.5% is found in nanoparticles prepared at 600°C.

Red (Eu3+), Green (Tb3+) and Ultraviolet (Gd3+) Emitting Nitrilotriacetate Complexes Prepared by One-step Synthesis

2014 ◽  
Vol 69 (2) ◽  
pp. 231-238 ◽  
Author(s):  
Ivan G. N. Silva ◽  
Hermi F. Brito ◽  
Ernesto R. Souza ◽  
Danilo Mustafa ◽  
Maria C. F. C. Felinto ◽  
...  
Keyword(s):  
Energy Transfer Process ◽  
Emission Spectra ◽  
X Ray Diffraction ◽  
Excited Triplet ◽  
X Ray ◽  
Intensity Parameters ◽  
One Step ◽  
Uv Excitation ◽  
Photoluminescence Behavior ◽  
The Eu

The [RE(NTA)(H2O)2]⋅(H2O) rare-earth complexes (RE3+: Eu, Gd, Tb and NTA: nitrilotriacetate) were synthesized and characterized by elemental analysis, thermogravimetry, X-ray diffraction, and infrared spectroscopy. The complexes show high crystallinity and thermostability. The photoluminescence behavior was studied based on the excitation and emission spectra, and luminescence decay curves. The compounds exhibit red (Eu3+), green (Tb3+) and UV (Gd3+) monochromatic emissions under UV excitation. The NTA ligand acts as luminescence sensitizer in the ligand-to- RE3+ intramolecular energy transfer process, owing to the fact that the first excited triplet state (T1: 29 000 cm−1) is located above of the 5D0 (Eu3+) and 5D4 (Tb3+) emitting levels. The experimental intensity parameters Ωλ (λ: 2 and 4) for the Eu3+ NTA complex were calculated, and the results are discussed. The Gd3+-NTA complex exhibits a high-intensity emission band in the UV region (32 000 cm−1) assigned to the 6P7/2→8S7/2 intraconfigurational transition.

scholarly journals Analysis of luminescence of Eu3+ doped Lu2Ti2O7 powders with Judd-Ofelt theory

2015 ◽  
Vol 38-39 (1) ◽  
pp. 23-32 ◽  
Author(s):  
Katarina Vuković ◽  
Sanja Ćulubrk ◽  
Milica Sekulić ◽  
Miroslav D. Dramićanin
Keyword(s):  
Emission Spectra ◽  
Quantum Yields ◽  
Optical Parameters ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Ofelt Theory ◽  
The Face ◽  
Face Centered ◽  
The Eu

Abstract Eu3+ doped Lu2Ti2O7 particles of 6 to 10 nm in diameter are prepared by Pechini-type polymerized complex route based on polyesterification between citric acid (CA) and ethylene glycol. X-ray diffraction measurements confirmed that Eu3+ doped Lu2Ti2O7 powders crystallized in the face-centered cubic lattice (Fd3m). Emission spectra displayed characteristic 5D0 →7 FJ (J = 0, 1, 2, 3 and 4) spin forbidden f-f electronic transitions of the Eu3+ ions with the most pronounced emission coming from 5D0 →7 F2 and with the emission decays varying between 0.75 and 0.60 ms for samples doped with different concentration of Eu3+. The Judd-Ofelt theory was applied to the experimental data for the quantitative determination of optical parameters such as Ω2, Ω4 Judd-Ofelt parameters, radiative and nonradiative transition rates and emission quantum efficiency. It was observed that, for all the samples, Ω2 >> Ω4. The luminescence quantum yields were calculated by means of the Judd-Ofelt theory and the highest value 60.83 % is obtained for particles doped with concentration of 3 % Eu3+.

scholarly journals Absorption and Emission Spectra for C60 Anions

1994 ◽  
Vol 14 (1-3) ◽  
pp. 155-160 ◽  
Author(s):  
Tatsuhisa Kato
Keyword(s):  
Absorption Spectrum ◽  
Absorption Band ◽  
Theoretical Analysis ◽  
Room Temperature ◽  
Emission Spectra ◽  
Mirror Image ◽  
Ir Absorption ◽  
Near Ir ◽  
Laser Experiments ◽  
Ir Bands

Absorption spectra are detected for C60− and C602− produced electrolytically in solution at room temperature. Theoretical analysis of the spectrum of C60− by CNDO/S calculations gives an interpretation of the characteristic near-IR bands, the weak visible bands, and the strong bands in the UV region. The emission spectrum of C60− is a mirror image of the near-IR absorption band, and the detection of the emission reconfirms our original assignment of the absorption spectrum. The nature of the spectrum of C602− is characterized by a similar orbital picture to that of C60−. Further laser experiments of significance are proposed.

Study of Temperature Behavior of Luminescence Emission of LaVO4 and La1-xEuxVO4 Powders

2015 ◽  
Vol 230 ◽  
pp. 153-159 ◽  
Author(s):  
Oksana Chukova ◽  
Sergiy G. Nedilko ◽  
Sergiy A. Nedilko ◽  
Tetiana Voitenko ◽  
Olga Gomenyuk ◽  
...  
Keyword(s):  
Emission Spectra ◽  
Spectral Lines ◽  
Temperature Behavior ◽  
Precipitation Method ◽  
Temperature Range ◽  
Luminescence Emission ◽  
Electron Transitions ◽  
The Matrix ◽  
Co Precipitation ◽  
The Eu

The La1‑xEuxVO4 powders were synthesized by co-precipitation method. Emission spectra of the LaEuVO4 and La1‑xEuxVO4 powders consist of wide non-structural bands of the matrix emission and narrow spectral lines caused by inner f-f electron transitions in the Eu3+ ions, respectively. The both types of emission were studied within 8 – 300 K temperature range. Decomposition of spectra of the wide matrix emission on three bands has been carried out and temperature dependencies for each band were studied. Temperature behavior of the Eu3+ emission was investigated for lines assigned to different Eu3+ centres. Obtained dependencies are analyzed and discussed using proposed schemes of transitions in the VO43- groups and structure of the nearest surrounding of the Eu3+ emission centres.

scholarly journals Photocatalytic Activity and Optical Properties of Blue Persistent Phosphors under UV and Solar Irradiation

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
C. R. García ◽  
L. A. Diaz-Torres ◽  
J. Oliva ◽  
M. T. Romero ◽  
P. Salas
Keyword(s):  
Photocatalytic Activity ◽  
Annealing Temperature ◽  
Uv Light ◽  
Solar Irradiation ◽  
Photoluminescence Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Water Cleaning ◽  
Different Temperatures ◽  
The Eu

Blue phosphorescent strontium aluminosilicate powders were prepared by combustion synthesis route and a postannealing treatments at different temperatures. X-ray diffraction analysis showed that phosphors are composed of two main hexagonal phases: SrAl2O4and Sr3Al32O51. The morphology of the phosphors changed from micrograins (1000°C) to a mixture of bars and hexagons (1200°C) and finally to only hexagons (1300°C) as the annealing temperature is increased. Photoluminescence spectra showed a strong blue-green phosphorescent emission centered atλem=455 nm, which is associated with4f65d1→4f6  (8S7/2)transition of the Eu2+. The sample annealed at 1200°C presents the highest luminance value (40 Cd/m2) with CIE coordinates (0.1589, 0.1972). Also, the photocatalytic degradation of methylene blue (MB) under UV light (at 365 nm) was monitored. Samples annealed at 1000°C and 1300°C presented the highest percentage of degradation (32% and 38.5%, resp.) after 360 min. In the case of photocatalytic activity under solar irradiation, the samples annealed at 1000°C, 1150°C, and 1200°C produced total degradation of MB after only 300 min. Hence, the results obtained with solar photocatalysis suggest that our powders could be useful for water cleaning in water treatment plants.

26. Future Trends

2019 ◽  
pp. 581-612
Author(s):  
Justine Pila ◽  
Paul L.C. Torremans
Keyword(s):  
Theoretical Analysis ◽  
Critical Analysis ◽  
Free Market ◽  
Future Trends ◽  
European Level ◽  
The Future ◽  
Market Perspective ◽  
Technical Rules ◽  
The Eu ◽  
The Way

This chapter offers an outlook to the future of IP at the European level. The EU and its legal instruments primarily approach IP from a utilitarian free market perspective and that applies also to the way they look at the future. The chapter focuses primarily on that angle when it looks at how the European IP system could and should function in the future and which direction it is taking. In a sense it offers an opportunity for reflection and attempts to enhance the reader's insight in and understanding of IP by wrapping the critical analysis of its technical rules up in a more theoretical analysis.

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