Correlation between structure variation and luminescence red shift in YAG:Ce

Pan, Yuexiao; Wang, W.; Liu, G.K.; Skanthakumar, S.; Rosenberg, R. A.; Guo, Xinpeng; Li, Kewen K.

doi:10.1016/j.jallcom.2009.04.082

Cited by 92 publications

(47 citation statements)

References 15 publications

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“…For instance, a compression of the local lattice surrounding the Ce 3+ ions accompanying the expansion of the whole lattice was proposed in order to explain the red shift of the luminescence of Ce:YAG upon Gd 3+ -codoping. 10 Also in this line, codoping with Mg 2+ and Si 4+ red shifts the Ce emission 8 and a similar red shift was anticipated by codoping with Mg 2+ and Ti 4+ , but a blue shift was found instead and the luminescence was severely quenched. 5 Besides the manipulation of the luminescence of the Ce defects, codoping YAG with Ce and other rare earths finds other applications.…”

Section: Introductionsupporting

confidence: 70%

Ce and La Single- and Double-Substitutional Defects in Yttrium Aluminum Garnet: First-Principles Study

Muñoz‐García

Seijo

2011

J. Phys. Chem. A

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The atomistic structure, energetics, and electronic structure of single substitutional Ce and La defects and double substitutional Ce-La defects in Ce,La-codoped yttrium aluminum garnet (YAG) Y 3 Al 5 O 12 have been studied by means of first-principles periodic boundary conditions density-functional theory calculations. Single substitution of Y by Ce or by La produces atomistic expansions around the impurities which are significantly smaller than the ionic radii mismatches and the overall lattice distortions are found to be confined within their second coordination spheres.In double substitutional defects, the impurities tend to be as close as possible. La-codoping Ce:YAG provokes an anisotropic expansion around Ce defects. The Ce impurity introduces 4f occupied states in the 5.0 eV computed gap of YAG, peaking 0.25 eV above the top of the valence band, and empty 4f , 5d, and 6s states starting at 3.8 eV in the gap and spreading over the conduction band.La-codoping produces very small effects on the electronic structure of Ce:YAG, the most visible one being the decrease of covalent bonding with one of the oxygen atoms, which shifts 0.05Å away from Ce and gets 0.04Å closer to La in the most stable Ce-La double substitutional defect.

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Section: Introductionsupporting

confidence: 70%

Ce and La Single- and Double-Substitutional Defects in Yttrium Aluminum Garnet: First-Principles Study

Muñoz‐García

Seijo

2011

J. Phys. Chem. A

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“…7,41 Although early ab initio calculations gave a much lower energy for this level (42600 cm −1 ), 42 which could apparently justify the assignment, they lacked dynamic correlation effects within the (CeO 8 ) 13− cluster, which are very important for spectroscopic calculations, and they used a crude embedding potential for YAG, just made of point-charges, which is now known to be insufficient for these materials. 43 The mentioned assignment has also been revised by Tanner et al, 44 who concluded that the 37000 cm −1 band is not due to Ce 3+ and supported the earlier assignment of Blasse and Bril, 1 also made by Zhao et al, 45 Let us now discuss the shifts of the 4f → 5d transitions of Ce:YAG upon La-codoping.…”

Section: Details Of the Calculationsmentioning

confidence: 99%

“…In effect, red shifts of the 5d → 4f luminescence of Ce:YAG have been found to appear as a consequence of La-codoping, 8 as well as of Gd-codoping, 1,4,[8][9][10] and red shift of the first 4f → 5d absorption has also been observed upon Gd-codoping. 1 The reasons behind the shifts are thought to be mostly structural and the same for Gd and La codopings; 7,8 we will analyze below these reasons in the case of 7,9 In any case, we think the computed red shift might be overestimated, because Tien et al 9 obtanied an approximate rate of 80 cm −1 red shift per 10 atom % of Gd codoping for the excitation peak of Ce,Gd:YAG, whereas the theoretical 220 cm −1 red shift corresponds to 4.1 atom% of La codoping and La produces smaller red shifts than Gd. 8 Blasse and Bril 1 also measured the effect of Gd-codoping on the second 4f → 5d absorption of Ce:YAG, which resulted to be a blue shift, in opposition to the red shift of the first absorption.…”

Section: Details Of the Calculationsmentioning

confidence: 99%

“…1,2 Controlling the color of these devices is considered one of the important issues governing the success of these technologies 3 and one of the methods used for this purpose is codoping. [4][5][6][7] Codopants are long ago known to be able to act as co-activators 6 and as wavelength shifters. 1,[8][9][10] In the case of Ce:YAG, Gd 3+ and La 3+ are known to shift the 5d → 4f yellow luminescence of the Ce 3+ defects to longer wavelengths (red shift), whereas codoping with Ga 3+ and In 3+ shifts the luminescence to shorter wavelengths (blue shift).…”

Section: Introductionmentioning

confidence: 99%

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Structural effects and4f−5dtransition shifts induced by La codoping in Ce-doped yttrium aluminum garnet: First-principles study

et al. 2010

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According to first-principles calculations performed on Ce-doped and Ce,La-codoped yttrium aluminum garnet (YAG) Y 3 Al 5 O 12 , the effect of La-codoping on the local structure around Ce defects in Ce:YAG is an anisotropic expansion in overall, in opposition to recent propositions of local lattice compression. Its effect on the lowest Ce 3+ 4f → 5d transition is found to be a red shift, in agreement with experiments. The red shift is the result of a decrease of the difference between the energy centroids of the 5d 1 and 4f 1 configurations and an increase of the effective ligand field on the Ce-5d shell associated with electronic effects of La substituting for Y. These effects are mitigated by the ligand field decrease associated with the local expansion around Ce, which gives a blue shift contribution of a smaller value. The behavior of the energy difference between the centroids of the configurations cannot be anticipated by the usual model for this quantity, in spite of its usefulness to rationalize 5d → 4f luminescences. The second 4f → 5d transition is found to be blue shifted upon La-codoping, also in agreement with experiments.

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“…-doped YAG, the study by Pan et al [51], who reported on the correlation between the red-shift of emission to the long-range crystalline structure of the same material, and the study by Furman et al [52], who showed that the quantum efficiency of YAG:Ce 3? is related to the degree of crystallinity.…”

Section: Case Studiesmentioning

confidence: 95%

Inorganic Phosphor Materials for Lighting

2016

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This chapter addresses the development of inorganic phosphor materials capable of converting the near UV or blue radiation emitted by a light emitting diode to visible radiation that can be suitably combined to yield white light. These materials are at the core of the new generation of solid-state lighting devices that are emerging as a crucial clean and energy saving technology. The chapter introduces the problem of white light generation using inorganic phosphors and the structureproperty relationships in the broad class of phosphor materials, normally containing lanthanide or transition metal ions as dopants. Radiative and non-radiative relaxation mechanisms are briefly described. Phosphors emitting light of different colors (yellow, blue, green, and red) are described and reviewed, classifying them in different chemical families of the host (silicates, phosphates, aluminates, borates, and non-oxide hosts). This research field has grown rapidly and is still growing, but the discovery of new phosphor materials with optimized properties (in terms of emission efficiency, chemical and thermal stability, color, purity, and cost of fabrication) would still be of the utmost importance.

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Correlation between structure variation and luminescence red shift in YAG:Ce

Cited by 92 publications

References 15 publications

Ce and La Single- and Double-Substitutional Defects in Yttrium Aluminum Garnet: First-Principles Study

Ce and La Single- and Double-Substitutional Defects in Yttrium Aluminum Garnet: First-Principles Study

Structural effects and4f−5dtransition shifts induced by La codoping in Ce-doped yttrium aluminum garnet: First-principles study

Inorganic Phosphor Materials for Lighting

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