【作者】 牛文斌；

【导师】 张淑芬； 武素丽；

【作者基本信息】 大连理工大学 ， 应用化学， 2012， 博士

【摘要】 稀土氟化物上转换多色发光纳米材料由于其独特的光学性能、优良的化学和生理性能,在彩色显示、光子器件、生物医学等领域具有广阔的应用前景。本文分别通过控制稀土氟化物上转换纳米粒子的表面配体组成、结晶度以及晶格声子能量,改变镧系发光中心离子能级之间发生无辐射弛豫的几率,建立了三种具有普遍性的调节稀土氟化物纳米材料上转换多色发光的新方法。在稀土氟化物上转换纳米粒子合成过程中,通过简单地改变反应体系中两种长链配体的组成,建立了一种通过控制表面配体调节稀土氟化物纳米粒子上转换多色发光的新方法,实现了同一镧系离子的上转换多色发光输出。利用1H-NMR、FT-IR和系列对照实验对NaYF4:Yb, Er粒子合成过程中溶剂体系的相互作用和粒子表面配体进行了详细的跟踪分析,发现油酸和十八胺之间发生了酰胺化反应,并随着体系中油酸和十八胺比例的变化,络合到粒子表面配体中酰胺化产物的相对含量发生变化,引起NaYF4:Yb, Er纳米粒子发光颜色从红、橙红、黄、黄绿到绿色的连续精细变化。该方法不但可用于Er3+、Ho3+和Tm3+等镧系离子的多色发光调节,而且可进一步拓展到不同的基质(如NaGdF4和NaLuF4)和由十八胺和油酸酰胺两种配体组成的反应体系中。论文设计并验证了一种通过控制反应温度和时间调节粒子的结晶度,进而调节稀土氟化物纳米粒子上转换多色发光的新方法。研究了体系反应温度和时间对氟化物上转换纳米粒子的内部缺陷和结晶度的影响,并通过系列对照实验、高分辨TEM照片和Williamson-Hall方法计算拟合等,证明了粒子结晶度的变化引起产物出现多色发光。同样,该方法也可实现对NaYF4:Yb,Ho和NaYF4:Yb,Tm纳米粒子上转换发光颜色的调节。论文设计并验证了一种以硝酸铵作为氧源,通过改变其加入量控制基质材料中氧含量来调节晶格声子能量,进而调节镧系离子掺杂的上转换材料的多色发光的普遍性方法,并通过上转换发光光谱、X射线荧光光谱、拉曼光谱等证明了该设计思路的合理性和正确性。同时,研究结果表明,只有硝酸铵作为氧源并且在250℃加入体系才能有效的实现稀土氟化物上转换材料发光颜色输出的调节。该方法可进一步用于Ho3+离子以及NaYF4和NaLuF4基质中Er离子的多色调节。将上述制备的多色上转换粒子与聚合物复合,进一步应用于彩色LED光转换剂,可有效的将近红外光转换为可见光,展示出丰富的发光颜色,有广泛应用前景。更多还原

【Abstract】 Due to their special upconversion luminescence performance, superior chemical and physiological properties, rare earth fluoride upconversion nanomaterials with multicolor output had been widely used in the fields of multicolor display, photonic devices, biomedical etc. In this thesis, we developed several new general protocols for the fine-tuning multicolor output of fluoride upconversion nanomaterials, based on changing the nonradiative relaxation probability of lanthanide luminescent ions, by controlling surface ligands, internal defects and crystallinity, and phonon energy, respectively.A general approach for the multicolor fine-tuning of fluoride upconversion nanoparticles (UCNPs) was developed by simply controlling the composition of two ligands during the synthesis procedure. The interaction between oleic acid (OA) and octadecylamine (OM) in reaction system and the surface ligands of nanoparticles were monitored and analyzed by1H-NMR and FT-IR spectroscopy. It is revealved that OA reacted with OM to form N-octadecyloleamide (OOA) before nucleation of fluoride nanoparticles. With the variation of OA/OM in reaction solution, the relative content of OOA molecule in the surface ligands was varied, which resulted in the multicolor output of NaYF4:Yb, Er nanoparticles with red, orange, yellow, yellow-green, green. This approach was not only expanded to the multicolor tuning of Ho3+and Tm3+, but also to the different host matrix (e.g. NaGdF4and NaLuF4) and ligand pairs (e.g. octadecylamine and oleamide).A new approach for the multicolor tuning of fluoride UCNPs was designed and testified based on controlling the crystallinity through tuning reaction temperature and time. The effects of reaction temperature and time on the internal defects and crystallinity were investigated, and it was demonstrated that the variation of crystallinity induced the multicolor emissions of nanoparticles through the control experiments, XRD, HR-TEM, and calculated results of Williamson-Hall methodology. Similarly, this method could also achieve the multicolor tuning of NaYF4:Yb,Ho and NaYF4:Yb,Tm UCNPs.A general new approach for the multicolor tuning of fluoride UCNPs was designed and testified by controlling phonon energy, which was achieved through tuning the relative content of oxygen impurities by changing the addition amount of NH4NO3. Upconvesion spectroscopy, X-ray fluorescence spectroscopy, Raman spectroscopy, and upconversion mechanism demonstrated the rationality of this strategy. In addition, the effects of addition temperature of NH4NO3and other oxygen sources on the upconversion luminescent performance were investigated. It is revealed that NH4NO3could be used as the oxygen source, and should be added into the reaction solution when the temperature was raised to250℃to achieve the effective multicolor tuning of fluoride UCNPs. This method could also be used for the multicolor tuning of Ho3+ion and Er3+ion in the host matrix of NaYF4and NaLuF4. Subsequently, as-prepared UCNPs were incorporated into the organic polymer and used as the color converters for LEDs with excellent performance, which could effectively convert the infrared light into visible ones, and these UCNPs exhibited great potential applications in many areas.更多还原