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Nanocomposite Phosphor Consisting of CaI2:Eu2+ Single Nanocrystals Embedded in Crystalline SiO2
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2017-11-15 00:00:00 , DOI: 10.1021/acsami.7b14132
Hisayoshi Daicho 1 , Takeshi Iwasaki 1 , Yu Shinomiya 1 , Akitoshi Nakano 2 , Hiroshi Sawa 2 , Wataru Yamada 2 , Satoru Matsuishi 3 , Hideo Hosono 3
Affiliation  

High luminescence efficiency is obtained in halide- and chalcogenide-based phosphors, but they are impractical because of their poor chemical durability. Here we report a halide-based nanocomposite phosphor with excellent luminescence efficiency and sufficient durability for practical use. Our approach was to disperse luminescent single nanocrystals of CaI2:Eu2+ in a chemically stable, translucent crystalline SiO2 matrix. Using this approach, we successfully prepared a nanocomposite phosphor by means of self-organization through a simple solid-state reaction. Single nanocrystals of 6H polytype (thr notation) CaI2:Eu2+ with diameters of about 50 nm could be generated not only in a SiO2 amorphous powder but also in a SiO2 glass plate. The nanocomposite phosphor formed upon solidification of molten CaI2 left behind in the crystalline SiO2 that formed from the amorphous SiO2 under the influence of a CaI2 flux effect. The resulting nanocomposite phosphor emitted brilliant blue luminescence with an internal quantum efficiency up to 98% upon 407 nm violet excitation. We used cathodoluminescence microscopy, scanning transmission electron microscopy, and Rietveld refinement of the X-ray diffraction patterns to confirm that the blue luminescence was generated only by the CaI2:Eu2+ single nanocrystals. The phosphor was chemically durable because the luminescence sites were embedded in the crystalline SiO2 matrix. The phosphor is suitable for use in near-ultraviolet light-emitting diodes. The concept for this nanocomposite phosphor can be expected to be effective for improvements in the practicality of poorly durable materials such as halides and chalcogenides.

中文翻译:

CaI 2:Eu 2+单纳米晶体嵌入晶体SiO 2中的纳米复合荧光粉

在基于卤化物和硫属化物的磷光体中获得了高发光效率,但是由于它们的化学耐久性差,所以它们是不切实际的。在这里,我们报告了一种卤化物基纳米复合磷光体,具有出色的发光效率和足够的耐用性以供实际使用。我们的方法是将CaI 2:Eu 2+的发光单纳米晶体分散在化学稳定的半透明晶体SiO 2基质中。使用这种方法,我们通过简单的固态反应通过自组织成功地制备了纳米复合荧光粉。6 H多型(值)CaI 2:Eu 2+的单纳米晶体不仅在SiO 2无定形粉末中而且在SiO 2玻璃板中都可以产生约50nm的直径。纳米复合磷光体是在CaI 2助熔剂效应的影响下在由无定形SiO 2形成的结晶SiO 2中残留的熔融CaI 2固化后形成的。所得纳米复合磷光体在407 nm紫光激发下发出亮蓝光,内部量子效率高达98%。我们使用阴极荧光显微镜,扫描透射电子显微镜和X射线衍射图的Rietveld精细化方法来确认蓝色发光仅由CaI 2:Eu产生2+个单纳米晶体。该磷光体具有化学耐久性,因为其发光位点嵌入了晶体SiO 2基质中。磷光体适用于近紫外发光二极管。可以预期这种纳米复合磷光体的概念对于改善耐用性差的材料(例如卤化物和硫属元素化物)的实用性是有效的。
更新日期:2017-11-15
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