New Perspective in Garnet Phosphor: Low Temperature Synthesis, Nanostructures, and Observation of Multimodal Luminescence

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• 作者：Kavita Mishra ; Sunil Kumar Singh ; Akhilesh Kumar Singh ; Monika Rai ; Bipin Kumar Gupta ; Shyam Bahadur Rai
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：September 15, 2014
• 年：2014
• 卷：53
• 期：18
• 页码：9561-9569
• 全文大小：544K
• ISSN：1520-510X

文摘

Herein, we report a new concept for garnet materials in terms of the synthesis of nanocrystalline structure at low temperatures and its multimodal luminescence processes. Terbium- and ytterbium-ion-codoped yttrium gallium garnet nanophosphors have been synthesized via solution combustion technique; nearly pure phase nanophosphor samples were obtained. The synthesized nanophosphor shows efficient multimodal upconversion (UC), downshifting (DS), and quantum cutting (QC)/downconversion (DC) luminescence, which is a new paradigm in garnet material. The garnet nanophosphor shows strong green emission through DS and UC processes both. Furthermore, cooperative energy transfer (CET) has been described in detail, and a possible mechanism for the QC process is also proposed. A UV/blue photon absorbed by Tb³⁺ ion splits into two near-infrared photons (wavelength range 900鈥?040 nm), emitted by a Yb³⁺ ion pair, with an efficiency of more than 100%. The Yb³⁺ concentration dependent ET from Tb³⁺ to Yb³⁺ has been verified using time domain analysis. An ET efficiency as high as 28% and a corresponding QC efficiency of about 128% (for 15 mol % of Yb³⁺ concentration) have been attained. Such a multimode emitting nanophosphor could be very useful in display devices and for enhancing the conversion efficiency of next generation solar cells via spectral modification etc.