【作者】 贾若琨；

【导师】 白玉白； 李铁津； 王德军；

【作者基本信息】 吉林大学 ， 物理化学， 2005， 博士

【摘要】 近年来,人们开始对荧光标记材料产生了浓厚的兴趣,特别是随着纳米技术的发展,能够进行生物标记的无机纳米晶成为人们追逐的热点,但是由于生物背底同样会产生荧光从而对荧光检测形成干扰,于是不会产生背底干扰的稀土上转换纳米发光标记材料引起了人们的注意。目前世界上上转换纳米荧光材料正处在发展阶段,材料的选择和合成有待于深入细致的研究。本文对上转换发光纳米晶的选择和合成做了系统的讨论。具体内容如下: 在丁二醇相中合成了ZrO2:Er3+,Yb3+纳米晶,使得晶化温度大大降低。由于ZrO2合成难度较大,在水相中极易聚集,同时晶化温度非常高,一般都在1000℃以上。在这个温度下更难得到纳米尺寸的材料,因此采用热溶剂法既可以避免合成时的聚集,有能够降低晶化的温度,是一种理想的合成方法。除了对合成方法进行研究外,同时对上转换的理论进行了细致的研究,第一次做了荧光峰位的精细指认。首次采用微波法合成Y2O3:Er3+,Yb3+纳米晶,得到的材料从尺寸到亮度都比ZrO2:Er3+,Yb3+纳米晶更为优越。细致讨论了发光颜色在不同的合成条件下的变化。利用模板技术合成了花瓣形状和叶片形状的材料,其表面亲水性检测的结果证实,两种不同形状的材料表面的可湿性差别巨大,花瓣形材料的表面为超亲水表面,叶片形材料的表面为超疏水表面。在水相中合成了NaYF4:Er3+,Yb3+纳米晶,得到了目前为止科学工作者发现的发光效率最高的上转换材料,探讨了几种条件对发光的影响,初步研究了上转换材料同磁性粒子的结合。荧光显微镜表征观察到了较为明亮的发光,细胞毒性实验证实这种上转换材料没有毒性。更多还原

【Abstract】 There has been considerable research on upconverting phosphors since initial interest in the late 1950s. An upconverting phosphor is one which takes multiple photons of lower energy and converts them to one photon of higher energy (this is an anti-Stokes process). Much of the early work was aimed at producing upconverting phosphor lamps by coupling the phosphors with light emitting diodes (LED), though the research did not yield viable products. More recently, there has been a resurgence of interest in upconverting phosphors and an extremely successful and widely utilized photonic application of rare earth elements is in the area of optical fiber-based telecommunications. Fiber optics has been a revolutionary force in the telecommunications industry. The critical component in this application is the Er ion doped fiber amplifier. Recently, the upconverting phosphor technology (UPT) has been applied to produce the lateral flow test strips. Upconverting Phosphor is the same usefull biological label as quantum dot. Upconverting transfer efficiency lies on phonon energy. Phonons are lattice vibrations in a material that can provide nonradiative decay pathways to suppress upconversion luminescence. To overcome the phonon decay problem it is necessary to choose a lattice that has much lower phonon energy. Oxide, fluoride, chloride and fluorochloride compounds are all the suitable materials for this purpose, but fluoride and chloride tend to deliquesce and present poor mechanical properties; and it is difficult to synthesize fluorochloride compounds. Therefor, oxide is often to be chosen as matrices. ZrO2, Y2O3, NaYF4 are suitable matrices with high chemical stabilization. Though NaYF4 is a kind of fluoride, it is still stable as oxide, has very high transfer efficiency. This article studied the three matrices and prepared the corresponding upconverting materials by using new prepared methods, studying their property and the upconverting mechanism. (1) Preparation of ZrO2: Er3+,Yb3+ nanocrystals ZrOCl2·8H2O (AR, Shanghai Chemical Reagent Corp.) and Er2O3 (GR) were used as the starting materials. Er2O3 was dissolved by nitric acid, and then precipitated by ammonia. Erbium acetate was obtained by dissolving the precipitate in acetic acid. To synthesize ZrO2:Er3+ nanoparticles, first, 7.5 g ZrOCl2·8H2O was added to the 80 ml 1,3-butadinol and stirred for 30 min at 200 ℃, then a stoichiometric amount of solid erbium acetate was added into the solution and the system was further stirred for 3 h at 200 ℃. The resulting sol was gelled by the controlled addition of 4 g NaOH. Then the gel particles were separated by centrifugation followed by washing with acetone. The product was dried at 60 ℃in air for 12 h and then calcined at 500 ℃for 2 h. The crystallization temperature is reduced to 500℃. X-ray diffraction (XRD) spectra show there exists monoclinic and cubicZrO2 phases. Green, yellow and red lights are seen from the upconverting luminescence spectra under 980nm excitation. The results confirm that upconverting emission is due to excited-state absorption (ESA) and energy transfer upconverting (ETU) process. (2) Preparation of Y3O2: Er3+,Yb3+ nanocrystals The starting materials are hexamethylenetetramine (AR, Aldrich), Y2O3 (GR), EDTA, Er2O3 (GR), and Yb2O3 (GR). R2O3 (R=Y, Er, Yb) were dissolved by nitric acid, and then precipitared by ammonia. (CH3COO)3R were obtained by dissolving the precipitate in acetic acid. To synthesize Y2O3:Er3+,Yb3+ nanocrystals, first, 1.55 g Yttrium acetate and 2 g EDTA were dissolved in 80 ml water in a beaker and a stoichiometric amount of solid erbium acetate and ytterbium acetate were added in to the solution under a quick stir. Then 20 ml 0.4 M hexamethylenetetramine solution was added and the solution was transparent. The solution was exposed to microwave radiation at a power of 300 W. The microwave irradiation was operated 30 second cycles ( on for 20 s, off for 10 s) until the turbidity was observed. The whole microwave irradiation process will be within 5 minutes. Then the turbidities were separated by centrifugation followed by washing 3 times. The product was dried at 60 ℃in air for 4 h and then calcined at 1000 ℃for 1 h. Erbium, Ytterbium codoped Y2O3 (Y2O3:Er3+,Yb3+) nanocrystals are prepared by microwave method. The reactive time is shortened to several minutes. X-ray diffraction (XRD) spectra show there no crystalline change when the fired temperature varies or doped concentration changes. The results confirm that what influences the color of emission is doped concentration and fired temperature. (3) Template Synthesis and Wettability Properties of large-scale更多还原