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首页> 外文期刊>RSC Advances >Enhanced luminescence efficiency of aqueous dispersible NaYF4:Yb/Er nanoparticles and the effect of surface coating
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Enhanced luminescence efficiency of aqueous dispersible NaYF4:Yb/Er nanoparticles and the effect of surface coating

机译：增强含水分散性NayF4：Yb / ER纳米颗粒的发光效率及表面涂层的效果

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摘要

In a general approach, we designed and synthesized monodisperse, well-defined, highly emissive and aqueous dispersible NaYF4:Yb/Er upconversion nanoparticles, and thereafter their surfaces were coated with inert NaYF4 and silica layers. The crystalline phase, morphology, composition and optical properties of the as-synthesized samples were well characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis absorption (UV-Vis), optical band gap energy, Fourier-transform infrared spectroscopy (FT-IR) and upconversion luminescence spectra, respectively. It is found that the synthesized hexagonal phase nanoparticles have a highly crystalline spherical shape, and are monodisperse with narrow size distribution. They can easily disperse in nonpolar cyclohexane solvent to form transparent colloid solutions. The optical band gap energy clearly shows the effect of surface coating of inert inorganic and porous silica layers surrounding the surface of seed core-nanoparticles due to the increase the crystalline size. The upconversion luminescence intensity was remarkably improved after the formation of a passive NaYF4 layer due to the decrease of non-radiative rate arising from the surface/defects of the particles in the form of surface dangling bonds and capping agents. The growth of the silica shell after inert shell formation and the emission intensity of Er3+ transitions were little affected with respect to inert shell coated core/shell nanoparticles, indicating that silica has been effectively grafted surrounding the core/shell nanoparticles. Our results indicate that surface coating of inactive and silica shells is a key step in producing upconversion nanocrystals with increased brightness for a variety of upconversion luminescence bioimaging and biosensing applications.
机译：在一般的方法中，我们设计和合成了单分散，定义的高发光和水分散性Nayf4：Yb / ER上转化纳米颗粒，然后将它们的表面涂覆有惰性NayF4和二氧化硅层。通过X射线衍射（XRD），透射电子显微镜（TEM），UV-Vis吸收（UV-VI），光带隙能量，X射线衍射（XRD）的结晶相，形貌，组成和光学性能良好地表征。傅里叶变换红外光谱（FT-IR）和上变发光光谱。发现合成的六方相纳米颗粒具有高结晶的球形，并且是具有窄尺寸分布的单分散。它们可以容易地分散在非极性环己烷溶剂中以形成透明的胶体溶液。光带间隙能量清楚地显示出惰性无机和多孔二氧化硅层的表面涂层由于晶体尺寸增加而围绕种子核心纳米颗粒表面的围绕的表面涂层。由于表面悬挂粘合剂和覆盖剂的形式而产生的非辐射速率降低，在形成无源NayF4层之后显着改善了上转换发光强度。惰性壳形成后的二氧化硅壳的生长和ER3 +过渡的发射强度对惰性壳涂覆的核/壳纳米颗粒很少受到影响，表明二氧化硅已经有效地接枝围绕芯/壳纳米颗粒。我们的结果表明，无活性和二氧化硅壳的表面涂层是产生上转化纳米晶体的关键步骤，其具有增加的亮度，用于各种上变化发光生物成像和生物传感应用。

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  • 来源
    《RSC Advances》 |2016年第26期|共9页
  • 作者

    Ansari Anees A.; Yadav Ranvijay; Rai S. B.;

  • 作者单位

    King Saud Univ King Abdullah Inst Nanotechnol Riyadh 11451 Saudi Arabia;

    Banaras Hindu Univ Dept Phys Varanasi 221005 Uttar Pradesh India;

    Banaras Hindu Univ Dept Phys Varanasi 221005 Uttar Pradesh India;

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  • 正文语种 eng
  • 中图分类 化学;
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