Fluorescent Ag+-exchanged zeolite nanoparticles with improved photoluminescence properties via X-ray irradiation
Fluorescent Ag+-exchanged zeolite nanoparticles with improved photoluminescence properties via X-ray irradiation
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DOI：
10.1016/j.jlumin.2017.12.028
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发表时间：
2018-04
影响因子：
3.6
通讯作者：
Kohei Taiji;Yoshiki Iso;T. Isobe
中科院分区：
文献类型：
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作者：
Kohei Taiji;Yoshiki Iso;T. Isobe
荧光八面沸石(FAU)-Y型银离子交换沸石是一种无稀土的荧光粉，具有较高的光致发光量子产率，可将近紫外光(近紫外光)转换为可见光。在这里，我们将重点放在纳米荧光分子筛作为光电子器件的波长转换器上。由于X射线辐照不具有其他处理方法的缺点，如热处理后纳米颗粒的聚集和烧结、化学还原后吸收可见光的银粒子过度生长以及高能电子束辐照沸石的非晶化等，制备的Ag+交换沸石纳米颗粒被X射线辐照以改善其发光性能。采用无模板剂水热合成法制备了FAU-Y沸石纳米颗粒，并通过Na+与Ag+的离子交换得到了荧光的Ag+交换沸石纳米颗粒。用商用台式设备的X射线对制备的Ag+交换沸石纳米颗粒进行了辐照。经透射电子显微镜分析，制得的沸石纳米颗粒的平均粒径为35.7±12.6 nm。透射电子显微镜还证实，银团簇和/或银纳米粒子等与银有关的粒子是由Ag+生成和生长的，可能是在X射线照射下分子筛骨架上的氧化物离子伴随着还原而产生和生长的。经X射线照射后，PL的量子效率提高了3倍。荧光性质和电子自旋共振谱的分析表明，在X射线辐照下形成了荧光Ag42+团簇，导致了发光量子效率的提高。微米级的银离子交换沸石也观察到了类似的行为。因此，X射线辐照是改善银离子交换分子筛发光性能的一种有效方法。
Fluorescent Faujasite (FAU)-Y Ag+-exchanged zeolite is a lanthanide-free phosphor with a high photoluminescence (PL) quantum yield to convert near-ultraviolet (near-UV) to visible light. Here, we focused on nanometer-sized fluorescent FAU Ag+-exchanged zeolite as a wavelength converter for optoelectronic devices. The prepared Ag+-exchanged zeolite nanoparticles were irradiated with X-rays to improve their PL properties because X-ray irradiation does not possess the disadvantages of other treatments, such as aggregation and sintering of nanoparticles exposed to thermal treatment, excessive growth of silver particles with visible light absorption following chemical reduction, and amorphization of zeolite by high-energy electron beam irradiation. FAU-Y zeolite nanoparticles were prepared by template-free hydrothermal synthesis and then fluorescent Ag+-exchanged zeolite nanoparticles were obtained through the ion exchange of Na+with Ag+. The prepared Ag+-exchanged zeolite nanoparticles were irradiated by X-rays from a commercial tabletop device. The average size of the as-prepared zeolite nanoparticles was 35.7 ± 12.6 nm according to transmission electron microscopy (TEM) images. TEM also confirmed that Ag-related particles such as silver clusters and/or silver nanoparticles were generated and grew from Ag+, possibly through reduction accompanied with oxidation of oxide ions of the zeolite framework during X-ray irradiation. PL quantum efficiency was enhanced by X-ray irradiation by up to ~3 times. Analysis of PL properties and electron spin resonance spectra implied that fluorescent Ag42+clusters were formed under X-ray irradiation, resulting in the enhancement of PL quantum efficiencies. Similar behavior was also observed for micrometer-sized Ag+-exchanged zeolites. X-ray irradiation of fluorescent Ag+-exchanged zeolites is therefore a useful method to improve their PL properties.