2021 Fiscal Year Research-status Report
| Project/Area Number |
21K14409
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| Research Institution | National Institute for Materials Science |
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Principal Investigator |
許 健 国立研究開発法人物質・材料研究機構, 若手国際研究センター(ICYS), ICYS研究員 (10889918)
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| Project Period (FY) |
2021-04-01 – 2023-03-31
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| Keywords | 蛍光体 / 白色LED / 長残光 / 透光性セラミックス |
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| Outline of Annual Research Achievements |
In the first fiscal year, the research achievements can be mainly divided into two parts:(1) A series of garnet-based transparent ceramics are prepared by the solid-state reaction method and vacuum sintering. Among them, the GAGG:Ce-Cr samples are used to demonstrate the flicker suppression effects utilizing its typical persistent luminescence properties, achieving ~73.8% flicker suppression when 70% Ga3+ substituting Al3+ in the garnet host. Besides, similar YAGG:Cr-Eu garnet ceramics are also investigated to exhibit deep-red/NIR long persistent luminescence up to ~900 nm, acting as potential candidates for NIR AC-LEDs.(2) Benefiting from a novel phosphor screening method (single-particle-diagnosis approach), a new Eu2+-activated cyan-emitting sialon polytypoid phosphor was discovered.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Efficient flicker suppression has been demonstrated in a yellow emitting Ce3+ doped garnet phosphor under conventional 460 nm LED pumping at the AC-driven mode. Furthermore, when changing the activator of Ce3+ into Cr3+ and tailoring the crystal field strength of garnet hosts by Ga3+ substitution. Large emitting wavelength shifting from yellow to deep-red/NIR has been successfully realized, which form a solid step to the NIR AC-LED devices.
Besides, single-particle-diagnosis approach together with streak imaging based time-resolved spectroscopy give new opportunities to have deep insights into the luminescent mechanism of excited state of newly discovered um order single-particle phosphor, which generally can only be discussed in the phosphors of bulk form.
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| Strategy for Future Research Activity |
In the second fiscal year, the research plans can be mainly divided into two parts:(1) the selected YAGG:Cr-Eu garnet ceramics with long deep-red/NIR persistent luminescence will be combined with AC-driven blue LEDs to clarify its luminescent properties including flicker percentage, luminous efficiency etc, in order to have a comprehensive understanding of the NIR AC-LED devices.(2) Utilizing the unique microscope streak imaging system, more (oxy)nitride phosphors will be studied, especially in the single-particle form, to clarify site environment effects on luminescent properties (lifetime & emission band). Time-resolved spectroscopy of power dependence of commercial phosphors (YAG:Ce&CASN:Eu) will also be performed to understand the saturation mechanism under high-power laser excitation.
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| Causes of Carryover |
The [JPY 56,169]left in the first fiscal year was planed to use for the business trip to Kyoto Univ., doing the NIR spectroscopy measurements of some (ony)nitride samples on Mar. However, because of the corona virus situation, the trip was cancelled, and now it has already been used up to cover the business traveling fee to Kumamoto city on May, where I gave an oral presentation on [第38回希土類討論会].
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[Journal Article] Unraveling the Luminescence Quenching of Phosphors under High-Power-Density Excitation2021
Author(s)
Peng Zheng, Shuxing Li, Takashi Takeda, Jian Xu, Kohsei Takahashi, Rundong Tian, Ran Wei, Le Wang, Tian-Liang Zhou, Naoto Hirosaki, Rong-Jun Xie
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Journal Title
Acta Materialia
Volume: 209
Pages: 116813 1-11
DOI
Peer Reviewed
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