Afterglow Luminescence in Ce3+-Doped Y3Sc2Ga3O12Ceramics

Ueda, Jumpei; Aishima, Kotaro; Nishiura, Shotaro; Tanabe, Setsuhisa

doi:10.1143/apex.4.042602

Cited by 59 publications

(29 citation statements)

References 21 publications

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“…This activation energy can be explained by a thermally stimulated process from electron traps, which can be either Ce-bound exciton, oxygen vacancies, or anti-site defects. 16,18,19 We consider the temperature dependence of the PCE bands (5d 1 and 5d 2 ) in the Ce:YGG. In this material, the 5d 1 and 5d 2 levels are located within the conduction band, where the electron in the 5d levels are transferred to the conduction band directly without any thermally activated passes.…”

Section: E Activation Energy From 5d State To Conduction Bandmentioning

confidence: 99%

Analysis of Ce3+ luminescence quenching in solid solutions between Y3Al5O12 and Y3Ga5O12 by temperature dependence of photoconductivity measurement

Ueda¹,

Tanabe²,

Nakanishi³

2011

Journal of Applied Physics

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202

122

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Photocurrent excitation spectra were measured to investigate the quenching in the garnet solid solutions. Intense photocurrent excitation bands attributed to the lowest 5d 1 and the second lowest 5d 2 levels were observed in the Ce-doped Y 3 Al 2 Ga 3 O 12 (Ce:YAGG) and Y 3 Ga 5 O 12 (Ce:YGG). Based on the results of temperature dependence of photoconductivity, the 5d 1 and 5d 2 levels in the Ce:YAGG are found to be located below and within the conduction band, respectively, while both levels in the Ce:YGG are found to be located within its conduction band located at lower energy levels. In addition, the threshold of photoionization from the 4f level of Ce 3þ to the conduction band in the Ce:YAGG and Ce:YGG were estimated to be 3.2, and 2.8 eV, respectively. We conclude that the main quenching process in the Ce:YAGG is caused by the thermally stimulated ionization process with activation energy of 90 meV from the 5d 1 to the conduction band, and that in the Ce:YGG is caused by the direct ionization process from the 5d levels to the conduction band.

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Section: E Activation Energy From 5d State To Conduction Bandmentioning

confidence: 99%

Analysis of Ce3+ luminescence quenching in solid solutions between Y3Al5O12 and Y3Ga5O12 by temperature dependence of photoconductivity measurement

Ueda¹,

Tanabe²,

Nakanishi³

2011

Journal of Applied Physics

Self Cite

202

122

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“…This green emitting phosphor shows afterglow for several hours after the excitation has stopped, and has been extensively investigated [3,4,5]. Two decades after the discovery by Matsuzawa et al, the list of afterglow phosphors has grown, and in addition to the alkaline earth aluminates it now also includes, among others, silicates and sulfides doped with a wide variety of activators, such as Eu

^{2 +}

[6], Ce

^{3 +}

[7,8] or transition metal ions [9]. An important class of these materials are the red- and infrared-emitting persistent phosphors, which are quite scarce compared to other classes, but are highly desired in diverse applications, such as bioimaging and safety signage.…”

Section: Introductionmentioning

confidence: 99%

Counting the Photons: Determining the Absolute Storage Capacity of Persistent Phosphors

et al. 2017

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The performance of a persistent phosphor is often determined by comparing luminance decay curves, expressed in cd/m2. However, these photometric units do not enable a straightforward, objective comparison between different phosphors in terms of the total number of emitted photons, as these units are dependent on the emission spectrum of the phosphor. This may lead to incorrect conclusions regarding the storage capacity of the phosphor. An alternative and convenient technique of characterizing the performance of a phosphor was developed on the basis of the absolute storage capacity of phosphors. In this technique, the phosphor is incorporated in a transparent polymer and the measured afterglow is converted into an absolute number of emitted photons, effectively quantifying the amount of energy that can be stored in the material. This method was applied to the benchmark phosphor SrAl2O4:Eu,Dy and to the nano-sized phosphor CaS:Eu. The results indicated that only a fraction of the Eu ions (around 1.6% in the case of SrAl2O4:Eu,Dy) participated in the energy storage process, which is in line with earlier reports based on X-ray absorption spectroscopy. These findings imply that there is still a significant margin for improving the storage capacity of persistent phosphors.

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“…So far, the optical properties of Ce 3+ in many garnet host compositions have been studied. [5][6][7][8][9][10][11][12][13][14] When the dodecahedral site in Ln 3 Al 5 O 12 are changed from the smaller lanthanide, Ln ion to the larger Ln ion, for instance in the order of Lu, Y, Tb to Gd, the 5d 1 energy shifts to the lower energy and quenching temperature becomes much lower. 15,16 Therefore, the luminescence quantum efficiency of Ce 3+ :5d 1 -4f at room temperature can be decreased with increasing ionic radius of the dodecahedral site.…”

Section: Cementioning

confidence: 99%

Editors' Choice—Investigation of Luminescence and Photoacoustic Properties in Ce³⁺-DopedLn₃Al₅O₁₂(Ln= Lu, Y, Gd) Garnet

Ueda

Yagi

Tanabe

2016

ECS J. Solid State Sci. Technol.

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Optical and photoacoustic properties of Ce 3+ -doped lanthanide (Lu, Y, Gd) aluminum garnet were investigated. In the photoacoustic (PA) spectra, the 5d 1 (lowest 5d level) band of Ce 3+ was observed at around 450 nm in the obtained Ce 3+ -doped garnet samples. This result shows that a part of the excited energy is converted to thermal energy, which is generated by some nonradiative processes. In Y 3 Al 5 O 12 :Ce 3+ , the 5d 1 PA peak wavelength is shorter than the 5d 1 photoluminescence excitation peak wavelength, which indicates that part of the heat generation is caused by the phonon relaxation process within 5d 1 state. The PA intensity and luminescence quantum efficiency of the Ce 3+ -doped gadolinium yttrium aluminum garnets ((Gd 0.5 Y 0.5 ) 3 Ce3+ -doped garnet materials have attracted a great deal of attention in w-LEDs and scintillators applications because of their intense broad absorption in a blue region, high quantum efficiency, and luminescence in various colors. These absorption and luminescence properties of the Ce 3+ ion are derived from the 4f-5d allowed transitions. The luminescence color variation is caused by the shift of 5d excited level by the nephelauxetic effect (centroid shift caused by covalency) and the crystal field splitting.1-4 The chemical formula of general garnet crystals can be expressed as {A} 3 [B] 2 (C) 3 O 12 , where {A}, [B] and (C) represent the cations at the dodecahedral, octahedral and tetrahedral sites, respectively. The dodecahedral site to which Ce 3+ occupies has the distorted square anti-prism structure with D 2 point-group symmetry, which results in the large crystal field splitting of 5d state. The split 5d levels are referred as 5d 1 , 5d 2 , 5d 3 . . . from the lowest 5d energy level. The crystal field strength and 5d splitting can be changed by varying the garnet component ions. So far, the optical properties of Ce 3+ in many garnet host compositions have been studied. [5][6][7][8][9][10][11][12][13][14] When the dodecahedral site in Ln 3 Al 5 O 12 are changed from the smaller lanthanide, Ln ion to the larger Ln ion, for instance in the order of Lu, Y, Tb to Gd, the 5d 1 energy shifts to the lower energy and quenching temperature becomes much lower. 15,16 Therefore, the luminescence quantum efficiency of Ce 3+ :5d 1 -4f at room temperature can be decreased with increasing ionic radius of the dodecahedral site. The decrease of quantum efficiency should cause excess heat generation through some nonradiative relaxation processes.Photoacoustic (PA) spectroscopy is one of the measurements to get information of heat generation after photon absorption. The heat flux generated by excitation light is transported in a sample and changes the surface temperature. As a result, the gas pressure in the photoacoustic chamber will be changed and the formed sound can be detected by a microphone. Grinberg et al. reported the PA spectrum of Y 3 Al 5 O 12 :Ce 3+ in a wide wavelength range between 265 nm and 570 nm and discussed the results with configuration coordinate diagram...

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Afterglow Luminescence in Ce³⁺-Doped Y₃Sc₂Ga₃O₁₂Ceramics

Cited by 59 publications

References 21 publications

Analysis of Ce3+ luminescence quenching in solid solutions between Y3Al5O12 and Y3Ga5O12 by temperature dependence of photoconductivity measurement

Analysis of Ce3+ luminescence quenching in solid solutions between Y3Al5O12 and Y3Ga5O12 by temperature dependence of photoconductivity measurement

Counting the Photons: Determining the Absolute Storage Capacity of Persistent Phosphors

Editors' Choice—Investigation of Luminescence and Photoacoustic Properties in Ce³⁺-DopedLn₃Al₅O₁₂(Ln= Lu, Y, Gd) Garnet

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Afterglow Luminescence in Ce3+-Doped Y3Sc2Ga3O12Ceramics

Cited by 59 publications

References 21 publications

Analysis of Ce3+ luminescence quenching in solid solutions between Y3Al5O12 and Y3Ga5O12 by temperature dependence of photoconductivity measurement

Analysis of Ce3+ luminescence quenching in solid solutions between Y3Al5O12 and Y3Ga5O12 by temperature dependence of photoconductivity measurement

Counting the Photons: Determining the Absolute Storage Capacity of Persistent Phosphors

Editors' Choice—Investigation of Luminescence and Photoacoustic Properties in Ce3+-DopedLn3Al5O12(Ln= Lu, Y, Gd) Garnet

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Afterglow Luminescence in Ce³⁺-Doped Y₃Sc₂Ga₃O₁₂Ceramics

Editors' Choice—Investigation of Luminescence and Photoacoustic Properties in Ce³⁺-DopedLn₃Al₅O₁₂(Ln= Lu, Y, Gd) Garnet