摘 要

尽管镧系掺杂上转换纳米材料（UCNPs）具有无比优越的物理化学特性使得其在资源能源和生物医疗领域有极大的应用潜力，但目前主要受限于原料昂贵、合成技术、上转换荧光强度低、生物相容性差等因素，而不能很好地推广应用，降低稀土上转换荧光材料的原料成本，灵活调控稀土上转换荧光材料的形貌和粒度，实现其上转换发光增强，改善其生物相容性是促进UCNPs应用推广的首要任务。针对上述局限，文中通过改变热分解法中前驱体的添加次序实现UCNPs的形貌和性能的调控。UCNPs的形状从球形到六方盘、片，其粒径从24到224 nm，其Gd和Yb Er在UCNPs固溶体中的含量也发生变化，进而影响其荧光和磁性能。并提出一种Mg² 掺杂策略有效提高上转换发光，并详细研究了Mg² 掺杂对纳米晶的晶体结构与粒径、上转换荧光以及磁性能的影响，在Mg² 掺杂的纳米晶表面生长一层壳层可产生协同效应而急剧地增强荧光，该纳米晶经亲水性配体（PAA和PEG）改性后，表现为低细胞毒性。最后，为降低UCNPs的制备成本，文中利用废弃荧光经三氟乙酸分步浸出技术分离得到Y的纯度可达81.44%以上，其Y的回收率为62.54%，成功制备了具有上转换性能的纯相β-NaYF₄材料，颗粒粒径为76 nm，呈六方盘状，其相对亮度为高纯物质制备的41.3%，还有待进一步改善。

关键词：镧系掺杂上转换；粒径调节；荧光增强；废弃荧光粉；UCNPs

Abstract

Although the lanthanide-doped upconversion nanoparticles (UCNPs) have excellent physical and chemical properties that have great potential in the field of resources, energy, and biomedicine, they are currently limited by expensive raw materials, synthetic techniques, low upconversion emissions, poor biocompatibility and other factors. It is the primary task to promote the application of UCNPs by reducing their cost of rare-earth raw material, regulating their shape and particle size flexibly, realizing their upconversion luminescence enhancement, and improving their biocompatibility. For fighting against the above limitations, in this thesis, the morphology and performance of UCNPs were tuned by changing the adding sequence of the precursors in the thermal decomposition method for the first time. The resulting nanocrystals, with different sizes ranging from 24 to 224 nm, are in the shape of spheres, hexagonal plates and flakes. The content of Yb Er and Gd in UCNPs solid solution also changes, which affects its luminescence and magnetic properties. A strategy of the luminescence enhancement in UCNPs via Mg² doping was discussed. The effect of Mg² doping on the crystal structure and particle size, upconversion emission and magnetic properties of nanocrystals was studied in detail. The Mg² -doped UCNPs grow a layer of shells that can produce synergistic effects to enhance the emissions significantly. UCNPs were modified by hydrophilic ligands (PAA and PEG) to exhibit low cytotoxicity. Finally, in order to reduce the preparation cost of UCNPs, the stepwise leaching of trifluoroacetic acid was used to treat the waste fluorescence, the purity of Y in the resulting solution is more than 81.44% and the recovery of Y form the waste fluorescence was 62.54%. And by using the resulting solution as the main raw material, the pure phase of β-NaYF₄ upconversion nanocrystal was obtained by thermal decomposition method, the particle size is 76 nm, the shape is hexagonal plate, and the relative brightness of this UCNPs is 41.3% of high purity raw material prepared UCNPs, yet to be further improved.

Key Words：Lanthanide-doped upconversion；size control；luminescence enhancement；waste phosphor；UCNPs

目 录

第1章 绪论 1

1.1 什么是上转换材料 1

1.2 镧系掺杂上转换材料 3

1.2.1 基质选择 3

1.2.2 镧系掺杂离子选择 5

1.3 镧系掺杂上转换纳米材料 6

1.3.1 应用前景 7

1.3.2 面临挑战 11

1.4 本文研究内容及意义 14

1.4.1 研究内容 14

1.4.2 研究意义 15

第2章 实验材料及方法 16

2.1 实验原料与试剂 16

2.2 实验所用仪器与设备 17

2.3 样品表征 18

第3章 改变前体的添加次序调控纳米晶的形貌及性能 19

3.1 引言 19

3.2实验步骤 19

3.3 结果与讨论 20

3.3.1 UCNPs的结构和形貌分析 20

3.3.2 UCNPs的成分及荧光磁性能分析 26

3.4 本章小结 28

第4章 Mg² 掺杂核壳结构增强上转换发光及其细胞毒性评价 29

4.1 引言 29

4.2 实验步骤 29

4.2.1 制备NaGdF₄:Yb/Er/Mg纳米晶 29

4.2.2 制备NaGdF₄:20%Yb,2%Er,13.5%Mg@NaGdF₄核壳结构 30

4.2.3制备水溶性UCNPs 30

4.2.4细胞毒性评估 30

4.3 结果与讨论 30

4.3.1 UCNPs的结构和形貌表征 30

4.3.2 UCNPs荧光和磁性能表征 33

4.3.3 细胞毒性评价 36

4.4 本章小结 37

第5章 回收废弃荧光粉中Y 降低UCNPs制备成本 38

5.1 引言 38

5.2 实验步骤 38

5.3 结果与讨论 39

5.3.1实验流程设计 39

5.3.2 产物结构与形貌表征 41

5.3.3 产物组成及荧光性能分析 42

5.4 本章小结 42

第6章 结论 44

参考文献 45

本科期间所获研究成果 52

致 谢 53

第1章 绪论

在人类文明和发展的进程中，发光材料经久不衰且具有举足轻重的作用，特别是在科技快速发展、信息爆炸的今天，它已成为一种人类生产生活中不可或缺的材料，广泛地应用于照明设备、显示屏、通信卫星、光学计算机、医疗（如生物分子探针、X射线断层扫描诊断即CT、荧光免疫检测分析、荧光活体成像等）、国防（如用于红外夜视仪的上转换材料）等诸多方面。为了满足不断增长的显示成像技术，发光材料已形成较大的生产规模并获得了可观的市场占有，从而产生了巨大的经济、社会效益。近年来，随着廉价红外半导体激光器的产生和发展，奇特的上转换发光材料的研究被推向研究热潮。