NaGdF4∶Yb3+/Ho3+/Ce3+共掺杂体系中红光和绿光比率增强设计

Effective Enhancement of Red to Green Ratio in NaGdF4∶Yb3+/Ho3+/Ce3+ Nanoparticle System

稀土离子掺杂氟化物纳米材料的红色上转换发光在彩色显示、生物成像、医学诊断、防伪标记等领域具有很大的应用潜力,尤其是小粒径的红色上转换纳米晶在医学诊断和生物成像等领域具有重要的应用价值。采用熔剂热方法成功地合成了一系列NaGd0.78-xF4∶Yb/Ho/Cex(x=0%,5%,10%,15%,20%,30%)上转换发光纳米晶,利用X射线粉末衍射仪(XRD)、透射电镜(TEM)、扫描电镜(SEM)以及荧光光谱仪等仪器对产物的物相结构、形貌和荧光性质进行了表征与研究,样品形貌均一,分散性好,呈现六角相,粒径大约在15~40nm,随着Ce^3+掺杂量的增大,粒径有所增大。在980nm红外光照射下,随着Ce^3+掺杂量的增加,Ho^3+红色光上转换显著增强,绿色光减弱,红色光和绿色光的比率从0.1224增加到3.2193,增加了将近26倍,产生了强烈的红色光,实现了绿色到红色的转换。最后,详细讨论了Ho^3+和Ce^3+离子之间可能的上转换发光机制。

The red upconversion luminescence of lanthanide-doped fluoride nanocrystals has great potential applications in the fields of color display,biological imaging,biomedicine,anti-counterfeiting,especially the small size red upconversion nanocrystals have important application in biomedicine and biological imaging. In this work,a series of NaGd0.78-xF4∶Yb/Ho/Cex (x =0%,5%,10%,15%,20%,30%) upconversion fluorescent nanocrystals were successfully synthesized by solvothermal process. The phase structure,morphology and fluorescence properties of the products were characterized and studied by using X ray powder diffractometer(XRD),transmission electron microscopy(TEM),scanning electron microscopy(SEM) and fluorescence spectrometer. The product has uniform morphology and good dispersibility,showing hexagonal phase. The particle size is about 15-40 nm. With the increase of Ce^3+ doping,the particle size increases. Under the excitation wavelength of 980 nm,the upconversion of Ho^3+ red light increased significantly,the green light weakened with the increase of concentration of Ce^3+ from 0% to 30%,the ratio of red light and green light increased from 0.122 4 to 3.219 3 ,increased by nearly 26 times,which realized the conversion of green to red. Finally,the possible upconversion emission mechanism between Ho^3+ and Ce^3+ ions is discussed in detail.