稀土离子掺杂铌酸盐微纳米材料的上转换发光及温度传感特性的研究

发布时间：2018-04-21 01:12

本文选题：微纳米材料 + 上转换　；参考：《太原理工大学》2017年硕士论文

【摘要】：近年来,稀土离子掺杂的上转换微纳米发光材料由于其独特的发光特性而被广泛地应用于激光、三维立体显示、荧光标签、温度传感、生物标记等领域,尤其在温度传感领域的研究与应用更是备受研究者们的广泛关注。目前,广泛使用的温度探测器件主要为传统的基于热接触式的温度测量设备。然而,在某些工作环境下,例如,强腐蚀性、电磁干扰环境下及微小快速移动物体的温度测量等,传统温度测量设备根本无法满足准确探测温度的要求。但是,相较于传统测量温度的技术,基于荧光强度峰值比的温度传感技术可以提供一种不受测量环境、分辨率和曝光时间等不同因素影响的温度探测,从而保证了温度探测的准确性与精度。众所周知,稀土离子具有丰富的能级结构。当相邻能级间距较小时,较高激发态能级通常可以被热布局,从而表现出温度依赖荧光发射强度的特性,因而可以用作光学温度传感材料。本文采用不同的化学方法合成了稀土离子掺杂的铌酸盐微纳米材料,并对其上转换发光机理和温度传感性质进行了详细地研究。最终通过深入的理论分析,揭示了影响基于上转换发光的光学温度传感灵敏度的主要因素。主要研究内容如下:(1)采用熔盐法首次合成了Yb~(3+)/Er~(3+)共掺的YNbO_4纳米荧光粉。X射线衍射、扫描电镜、透射电镜及高分辨透射电镜结果表明所合成荧光粉为单斜结构的YNbO_4,且颗粒直径约为35 nm。在980 nm激光的激发下,所制备的YNbO_4纳米荧光粉表现出较强的上转换发光强度。通过分析发光强度与激发功率之间的依赖关系,证实了绿色与红色上转换发光均为双光子上转换发光过程。基于Er~(3+)离子的2H11/2/4S3/2两个热耦合绿光能级的荧光峰值比技术研究了YNbO_4纳米荧光粉的光学温度依赖性质,并且通过调节掺杂离子的浓度实现了荧光粉传感灵敏度的调控,结果发现:随着Yb~(3+)掺杂浓度的增加,荧光粉的传感灵敏度逐渐减小。同时观察到:随着温度升高,上转换纳米荧光粉的发光颜色从黄色变成了绿色。(2)利用水热法合成了一系列不同浓度的Yb~(3+)/Er~(3+)共掺的NaNbO_3微纳米荧光粉,并研究了NaNbO_3:Yb~(3+)/Er~(3+)荧光粉的上转换发光性质与发光机理。X射线衍射及扫描电镜结果证实制备的荧光粉为纯相的NaNbO_3:Yb~(3+)/Er~(3+)荧光粉。上转换荧光光谱结果表明:在980 nm激光泵浦下,共掺Yb~(3+)/Er~(3+)离子的荧光粉表现出较强的绿光与红光发射,分别对应着Er~(3+)离子2H11/2,4S3/2→4I15/2的跃迁与4F9/2→4I15/2的跃迁。发光强度的功率依赖特性证明绿色与红色上转换发光均为双光子上转换过程。另外,测量了不同温度下的绿光上转换荧光光谱,并研究了不同浓度下NaNbO_3荧光粉的温度传感灵敏特性,结果表明:Yb~(3+)掺杂浓度越低,传感灵敏度越高。
[Abstract]:In recent years, rare-earth ion doped up-conversion micro-nano luminescent materials have been widely used in laser, three-dimensional display, fluorescent label, temperature sensing, biomarker and other fields due to their unique luminescence properties. Especially in the field of temperature sensing research and application is widely concerned by researchers. At present, the widely used temperature detector is mainly based on the traditional thermal contact temperature measuring equipment. However, in some working environments, such as strong corrosion, electromagnetic interference and temperature measurement of small and fast moving objects, the traditional temperature measurement equipment can not meet the requirements of accurate temperature detection. However, compared with the traditional temperature measurement technology, the temperature sensing technology based on the peak fluorescence intensity ratio can provide a temperature detection which is not affected by different factors, such as the measuring environment, the resolution and the exposure time, etc. Thus, the accuracy and accuracy of temperature detection are guaranteed. It is well known that rare earth ions have abundant energy level structures. When the distance between adjacent energy levels is small, the higher excited energy levels can usually be thermally distributed, thus showing the characteristics of temperature dependent fluorescence emission intensity, so they can be used as optical temperature sensing materials. In this paper, rare earth ions doped niobate nanocrystalline materials were synthesized by different chemical methods, and their up-conversion luminescence mechanism and temperature sensing properties were studied in detail. Finally, the main factors affecting the sensitivity of optical temperature sensing based on up-conversion luminescence are revealed by in-depth theoretical analysis. The main contents of this study are as follows: (1) the YNbO_4 nano-phosphors co-doped with Yb~(3 ~ (+ +) / Erton-3 were synthesized by molten salt method for the first time. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to prepare the YNbO_4 nano-phosphors. The results of transmission electron microscopy (TEM) and high resolution transmission electron microscopy (TEM) show that the synthesized phosphors are monoclinic YNbO _ s _ 4, and the particle diameter is about 35 nm. Under the excitation of 980nm laser, the YNbO_4 nanocrystalline phosphors exhibit strong up-conversion luminescence intensity. By analyzing the dependence between luminescence intensity and excitation power, it is proved that both green and red up-conversion luminescence are two-photon up-conversion luminescence processes. The optical temperature-dependent properties of YNbO_4 nanocrystalline phosphors were studied by using the fluorescence peak ratio technique of two thermally coupled green light levels of 2H11/2/4S3/2 based on Er~(3 ions, and the sensitivity of the phosphors was regulated by adjusting the concentration of doped ions. The results show that the sensitivity of phosphors decreases with the increase of doping concentration of Yb~(3. At the same time, it was observed that with the increase of temperature, the luminescence color of up-conversion nano-phosphors changed from yellow to green.) A series of NaNbO_3 microphosphors with different concentrations were synthesized by hydrothermal method. The upconversion luminescence properties and luminescence mechanism of NaNbO_3:Yb~(3 / Ern 3) phosphors have been studied. The results of X-ray diffraction and scanning electron microscopy show that the phosphors prepared are pure phase NaNbO_3:Yb~(3 / Erf3) phosphors. The upconversion fluorescence spectra show that the phosphors co-doped with Yb~(3 ~ + / er ~ (3) ~ (3) ions exhibit strong green and red emission, corresponding to the transition of 2H _ (11 / 2) S _ (3 / 2) 4I15/2 and 4F9/2 4I15/2, respectively, under the pump of 980nm laser. The power dependence of luminescence intensity shows that both green and red up-conversion luminescence are two-photon up-conversion processes. In addition, the up conversion fluorescence spectra of green light at different temperatures were measured, and the sensitive characteristics of temperature sensing of NaNbO_3 phosphors at different concentrations were studied. The results show that the lower the doping concentration is, the higher the sensing sensitivity is.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O482.31

【参考文献】