【作者】 韩海龙；

【导师】 杨利文；

【作者基本信息】 湘潭大学 ， 微电子学与固体电子学， 2009， 硕士

【摘要】 过去二十几年里,稀土掺杂上转换发光材料在三维立体显示、全固态激光器、红外探测等领域的广泛应用,引起了人们极大的研究兴趣。随着纳米科技的兴起,纳米上转换发光材料也成为上转换发光材料中新的研究热点,特别是作为生物荧光标签在生物检测领域具有广泛的应用前景。与传统染料标签相比,上转换荧光标签具有高灵敏性、抗漂白、高稳定性、环境影响小等优点。但稀土离子能级丰富,激发时常有多条谱线,而单带发射是生物标签实现多目标识别及多分子追踪的一个基本要求。另一方面,利用上转换白光纳米晶作为生物荧光标签,能够提供更多的同时检测通道,并能使荧光标签很好区别于环境色彩。目前关于稀土掺杂纳米晶上转换单一谱线及白光发射的报道却比较少,因此如何在稀土上转换材料中实现高纯单色发射或白光发射,提高识别效率成为当前上转换纳米荧光材料作为荧光探针在生物检测领域所面临的挑战之一。本文分别制备了稀土掺杂ZnO纳米晶和稀土掺杂NaYF4纳米棒粉末样品,结合Raman光谱、X射线衍射（XRD）、透射电镜（TEM）以及荧光光谱对样品的微结构和单带上转换可调荧光发射及上转换白光发射进行了研究。主要内容如下:第一部分采用化学燃烧法制备了一系列Er³⁺单掺和Er³⁺-Li⁺共掺杂ZnO纳米粉末样品,结合Raman光谱和XRD衍射光谱对样品的晶体结构进行了表征。结果表明热处理可以改善稀土掺杂ZnO纳米晶结晶质量,而Li⁺离子共掺杂能够有效促进稀土离子融入ZnO基质中。上转换荧光光谱则表明Er³⁺单掺样品在980nm激光激发下以红色上转换荧光（660nm）为主,而Er³⁺-Li⁺共掺杂样品则以绿光（535nm和557nm）为主,都呈现出良好的单色性。实验表明通过Li⁺离子共掺杂,可以有效调节Er³⁺掺杂ZnO样品的单带上转换荧光发射,有望作为多彩荧光生物标签得到应用。第二部分采用水热合成法190℃时制备了一系列高纯单一晶相的六角稀土掺杂的NaYF4纳米棒。其中Yb³⁺/Er³⁺/Tm3+及Yb³⁺/Ho3+/Tm3+三掺β-NaYF4纳米棒样品,在980nm激光激发下观察到了由上转换红、绿、蓝三基色拟合白光,样品的CIE色坐标值分别为（X=0.310, Y=0.340; X=0.316,Y=0.345）。不同激发功率密度下样品荧光光谱对样品上转换荧光特性分析表明Yb³⁺/Er³⁺/Tm3+及Yb³⁺/Ho3+/Tm3+三掺β-NaYF4纳米棒样品红、绿、蓝波段上转换荧光强度对激发功率密度的响应不一致,与Yb³⁺/Er³⁺/Tm3+三掺β-NaYF4白光样品相比,Yb³⁺/Ho3+/Tm3+三掺β-NaYF4白光样品有更宽的功率密度适用范围。更多还原

【Abstract】 In pase twenty years, rare-earth-doped materials have been extensively investigated because of the promising application in the flat-panel displays, solid-state lasers, infrared detection, and biological detection and so on. In recent years, with development of nanotechnology, lanthanide-doped upconversion nanocrystals have been developed as a new class of luminescent optical labels that have become promising alternatives to organic fluorophores and quantum dots for applications in biological assays and medical imaging. These techniques offer low autofluorescence background, large anti-Stokes shifts, sharp emission bandwidths, high resistance to photobleaching, and high penetration depthand temporal resolution. Especially, with the application of biological multicolor fluorescent labels in multi-parameter detection, imaging and tracking of multiple molecular targets, narrow band radiations with high efficient luminescence in different wavelength ranges are needed. On the other hand, the white light upcoversion nanocrystal can provide more simultaneous detection channel as biological fluorenscent labels, farther distinguish marks from environmental colours. However, few works are reported about single band UC emission and white UC emissions in lanthanide-doped nanocrystals with the purpose of fluorescent labels in biological applications. Based on this background, in this dissertation, a series of rare earth doped ZnO nanoparticle and NaYF4 one-dimensional structure were prepared by chemical combustion method and hydrothermal, respectively. The structural and optical properties of the prepared samples were studied using Raman spectra, x-ray diffraction （XRD）,? transmission electron microscopy （TEM） and up-conversion luminescent spectra, the influence of co-doped Li+ ions on the single band emission of ZnO:Er³⁺ nanocrystal and the influence of pump power desity on white UC luminescence of the NaYF4 was analyzed. The major contents of our study as follows:In the first part, Er³⁺ doped ZnO nanoparticle were prepared by chemical combustion method. The red up-conversion luminescence was observed under 980nm excitation. Furthermore, a luminescent switching between the main red UC emission at 660nm and green one centered at 535nm and 557nm assigned to the transitions of 2H11/2/ 4S3/2→4I15/2 was presented through Li+ co-doping.? The origin of luminescent switching could be attributed to the modification of local crystal field around Er³⁺ ions due to the introduction of Li+ ions, and should be a promising upconversion phosphor for optoelectronic or biological applications. ?In the second part, high-quality hexagonal phase rare-earth-doped NaYF4 nanorods was prepared by hydrothermal method at 190℃. Bright white light was produced under 980nm laser excitation through synthesis of red, green, blue upconversion luminescence in Tm3+/Ho3+/Yb³⁺ tridoped and Tm3+/Er³⁺/Yb³⁺ tridoped NaYF4 nanorods, respectively. The perfect white light with （X=0.310, Y=0.340） and （X=0.316,Y=0.345） in Tm3+/Ho3+/Yb³⁺ tridoped and Tm3+/Er³⁺/Yb³⁺ tridoped NaYF4 nanorods were obtained by adjusting the pump power density, respectively. Based on the power dependent spectral analyses,it was found that the pump power density response is different of red, green, blue emission in Tm3+/Ho3+/Yb³⁺ tridoped and Tm3+/Er³⁺/Yb³⁺ tridoped NaYF4 nanorods. and Tm3+/Ho3+/Yb³⁺ tridoped sample have much wider range of power density response, relatively.更多还原