Effects of Tb doping on the photoluminescence of Y2O3:Tb nanophosphors

Muenchausen, R. E.; Jacobsohn, L.G.; Bennett, B. L.; McKigney, Edward A.; Smith, James F.; Valdez, James A.; Cooke, D. W.

doi:10.1016/j.jlumin.2006.12.004

Cited by 84 publications

(69 citation statements)

References 30 publications

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“…PL spectra of the 5 Figure 7a does not show large differences between the normalized spectra, whereas the differences in Figure 7b are large. The peak at 544.2 nm is not the only one that shows C 3i character, the peaks at 548.1 nm, 550.3 nm and 552 nm also show C 3i character, albeit less than the peak at 544.2 nm.…”

Section: Figure 2 Ismentioning

confidence: 89%

“…It was discussed by Najafov et al 4 and measured by Muenchausen et al; 5 these latter authors found that the PL efficiency peaked at 0.5 Mol% in bulk Y 2 O 3 :Tb 3+ material, whereas for their nano-material with particle size of 35 nm it peaked at 1.5% Tb 3+ . Wang et al 6 found that the 5 were given by Ropp, 8 Najafov et al, 4 Muenchausen et al, 5 Meng et al, 9 Liu et al, 10 Ray et al, 11 Loitongbam et al 12 and Som et al 13 Most authors assigned the broad excitation band between 260 nm and 310 nm to a 4f 8 →4f 7 5d 1 transition in the Tb 3+ ion. Only Ray et al 11 and Loitongbam et al 12 designated this excitation band as a charge transfer (CT) band.…”

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confidence: 83%

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Symmetry-Related Transitions in the Photoluminescence and Cathodoluminescence Spectra of Nanosized Cubic Y₂O₃:Tb³⁺

Engelsen

Harris

Ireland

et al. 2015

ECS J. Solid State Sci. Technol.

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Herein the photoluminescence spectra of nanosized cubic Y 2 O 3 :Tb 3+ having Tb 3+ concentrations varying between 0.1 and 10 Mol% are described. Low temperature cathodoluminescence spectra from these materials recorded in a scanning transmission electron microscope are presented and discussed. By studying the photoluminescence-spectra recorded at room temperature and focused on the 5 D 4 → 7 F 5 (C 2 ) and 5 D 4 → 7 F 5 (C 3i ) transitions, at 542.8 and 544.4 nm respectively, it was found that the critical distance for energy transfer from Tb 3+ ions at C 3i lattice sites to Tb 3+ ions at C 2 lattice sites was 1.7 nm; at distances >1.7 nm, which prevail at low Tb 3+ concentration, this energy transfer virtually stops. The gradual change of the excitation spectra upon increasing the Tb 3+ concentration is also explained in terms of energy transfer from Tb 3+ at C 3i sites to Tb 3+ at C 2 sites. Cathodoluminescence spectra recorded at low temperatures with the scanning transmission electron microscope provided additional evidence for this radiationless energy transfer. Recently we published a study on the cathodoluminescence (CL) of nanosized cubic Y 2 O 3 :Tb 3+ particles; 1 reference to this work will be made as Part 1. We identified a few peaks in the CL spectra that are related to Tb 3+ at C 3i sites in cubic Y 2 O 3 (the structure is that of the mineral bixbyite). In Part 1, we have indicated the C 3i sites by S 6 . The vast majority of the spectral lines in the CL spectra of Y 2 O 3 :Tb 3+ arise from C 2 type transitions. We also found evidence that the two strongest emission lines in the 5 D 4 → 7 F 5 transition cluster at 542.8 nm and 544.4 nm are split when recorded at low temperature. These spectral data provided insight into the energy flow from Tb 3+ ions at C 3i lattice sites to Tb 3+ ions at C 2 lattice sites: the critical distance between a Tb 3+ (C 3i ) donor ion and Tb 3+ (C 2 ) acceptor ion was found to be 1.7 nm, which is about 5 times larger than the shortest distance between a cation at a C 3i site and a cation at a C 2 site.1,2 It is the objective of the work described herein to gain more insight into the studies reported in Part 1 by measuring the photoluminescence (PL) spectra at room temperature and the CL spectra in a scanning transmission electron microscope (STEM) at low temperatures.Many authors have reported on the PL spectrum of Y 2 O 3 :Tb 3+ ; here we shall mention only the most relevant publications on the spectroscopic characteristics of Y 2 O 3 :Tb 3+ . An important result in Part 1 was the doublet structure of the 542 nm and 544 nm lines, which became noticeable at a temperature of 103 K. A similar result was reported by Song and Wang, 3 who also found 4 lines between 541 and 545 nm at 83 K. At 274 K these lines coalesced into two peaks, in which the 542 nm peak still showed a shoulder. Najafov et al. 4 showed the doublet structure of the 542 nm and 544 nm lines in the PL spectra of Y 2 O 3 :Tb 3+ with various Tb 3+ concentrations at room temperature. In the spectrum presented...

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Section: Figure 2 Ismentioning

confidence: 89%

mentioning

confidence: 83%

Symmetry-Related Transitions in the Photoluminescence and Cathodoluminescence Spectra of Nanosized Cubic Y₂O₃:Tb³⁺

Engelsen

Harris

Ireland

et al. 2015

ECS J. Solid State Sci. Technol.

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“…In nanoparticles, several groups have found that the luminescence in nanopaticles persists at higher dopant concentrations than in bulk materials, [35][36][37][38] and sometimes even increases with increasing dopant concentration. Figure 20 shows the example of a Tb-doped Y 2 O 3 system in which for the smallest particles the luminescence continues to increase at concentrations far higher than for the much larger particles.…”

Section: Energy Transfer Among Ions In Nanoparticlesmentioning

confidence: 99%

Non-Radiative Processes in Crystals and in Nanocrystals

Collins

2015

ECS J. Solid State Sci. Technol.

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This paper discusses non-radiative processes that are relevant to the luminescence characteristics of optically active ions doped into insulators or large-gap semiconductors, with particular attention to how these processes are affected as the particle size is reduced from bulk single crystals to as small as a few nanometers. The non-radiative processes discussed in this article are thermal line broadening and thermal line shifting, relaxation via phonons between excited electronic states, vibronic emission and absorption, and phonon-assisted energy transfer. Given that one of the main effects of confinement in these particles is on the phonon density of states, we pay particular attention to how these non-radiative processes are altered due to the change in the phonon density of states as particle size decreases. Inorganic insulators doped with rare-earth ions and transition metal ions represent an important class of luminescent materials for many applications, including phosphors for lighting, scintillators, solid-state laser materials, bio-markers for imaging, and nanothermometry. Following excitation by radiation, the optical ions usually undergo some degree of non-radiative relaxation releasing a part or all of its energy to the lattice. During the non-radiative relaxation, all or part of the electronic energy initially stored in the optically active ion is converted into phonons.From the perspective of energy efficiency of luminescent materials, it may seem beneficial to attempt to eliminate non-radiative processes altogether. However, the conversion of electronic energy into heat energy following excitation is, in fact, desirable to many applications. Non-radiative processes play an important role in converting light from the blue LED into red and green light for white light generation in lamp phosphors, for efficient operation of many solid-state lasers, for energy transfer and multiphonon relaxation in bio-imaging, and also for the establishment of thermal equilibrium, the principle on which thermometry is based. For these technologies to be optimized, non-radiative processes must be controlled, or at least carefully considered. Thus, understanding these processes is of great interest to the luminescence community. The specific non-radiative processes addressed in this work are thermal line broadening, thermal line shifting, decay via a phonon from one electronic level to another, vibronic transitions, and phonon-assisted energy transfer.The main focus of this work is on how non-radiative processes are affected as the particle size decreases into the nano-regime. Generally speaking, the two main effects of going from the bulk to the nano are:(1) an increase in the surface to volume ratio, and (2) a reduction in the phonon density of states. Item (1) often leads to an increase in defect sites (mostly near the surface) and surface states, which in turn tends to decrease the luminescence efficiency as one goes from the bulk to the nano. This nonradiative process is outside the scope of this article. Item (...

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“…While semiconductor nanocrystals have been a subject of study for more than thirty years, investigations of wide band-gap insulating nanocrystals begun only recently (Tissue, 1998;Meltzer et al, 1998). Nanocrystals of Y 2 O 3 doped with europium or terbium were produced by condensation from gas phase (Bihari et al, 1997;Meltzer et al, 1999), sol-gel (Goldburt et al, 1997) or combustion (Muenchausen et al, 2007) methods. Gd 2 O 3 :Eu was produced by sol-lyophilization (Louis et al, 2003;Mercier et al, 2004Mercier et al, , 2006 and CBD (Cluster Beam Deposition) (Mercier et al, 2007) techniques.…”

Section: Introductionmentioning

confidence: 99%

“…Luminescence efficiency can also be affected by quantum confinement; in fact, in Y 2 O 3 :Tb an increase of Tb 3+ luminescence efficiency is observed by reducing particle size probably because of the decrease of non-radiative recombination phenomena (Goldburt et al, 1997). Moreover, the fluorescence time decay is strongly affected by refractive index of the inert host material (Meltzer et al, 1999) and quenching phenomena are shifted towards higher concentrations with respect to the single crystal (Muenchausen et al, 2007). Among reported attempts on preparation of such nanocomposite systems the fluoro-clorozirconate glass-ceramic can be mentioned: luminescence arises at Eu 2+ -containing BaCl 2 nanocrystals with average size of 14 nm, thus, the material possesses good transparency (Johnson et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Silicate Glass-Based Nanocomposite Scintillators

Nikl¹,

anský²,

Růžička³

et al. 2011

Advances in Nanocomposite Technology

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Effects of Tb doping on the photoluminescence of Y2O3:Tb nanophosphors

Cited by 84 publications

References 30 publications

Symmetry-Related Transitions in the Photoluminescence and Cathodoluminescence Spectra of Nanosized Cubic Y₂O₃:Tb³⁺

Symmetry-Related Transitions in the Photoluminescence and Cathodoluminescence Spectra of Nanosized Cubic Y₂O₃:Tb³⁺

Non-Radiative Processes in Crystals and in Nanocrystals

Silicate Glass-Based Nanocomposite Scintillators

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Effects of Tb doping on the photoluminescence of Y2O3:Tb nanophosphors

Cited by 84 publications

References 30 publications

Symmetry-Related Transitions in the Photoluminescence and Cathodoluminescence Spectra of Nanosized Cubic Y2O3:Tb3+

Symmetry-Related Transitions in the Photoluminescence and Cathodoluminescence Spectra of Nanosized Cubic Y2O3:Tb3+

Non-Radiative Processes in Crystals and in Nanocrystals

Silicate Glass-Based Nanocomposite Scintillators

Contact Info

Product

Resources

About

Symmetry-Related Transitions in the Photoluminescence and Cathodoluminescence Spectra of Nanosized Cubic Y₂O₃:Tb³⁺

Symmetry-Related Transitions in the Photoluminescence and Cathodoluminescence Spectra of Nanosized Cubic Y₂O₃:Tb³⁺