稀土纳米晶与PMMA复合材料上转换发光性质的研究

发布时间：2018-03-21 09:11

  本文选题：NaYF_4　切入点：Y_2O_3　出处：《长春工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：镧系元素掺杂的纳米晶体具有独特的光学性质,在体内成像、太阳能电池和3D显示等领域具有很多潜在的应用,引起了学术界的广泛关注。特别是氧化物和氟化物纳米晶由于其独特的光学性质、高化学稳定性和低声子能量等特点,常被用作纳米晶的主晶格材料。同时,合成的稀土纳米晶与高聚物结合的复合材料将会进一步推动稀土纳米晶的广泛应用。利用水热法成功合成了YF_3纳米晶、α-NaYF_4和β-NaYF_4混相纳米晶及β-NaYF_4纳米晶,通过在合成的氟化物纳米粒子中掺入Zn~(2+)离子及改变Zn~(2+)离子浓度,实现了YF_3到α-NaYF_4纳米晶和α-NaYF_4到β-NaYF_4纳米晶的晶相转变过程,相变主要是由于Zn~(2+)离子替代了Y~(3+)离子的晶格位点导致了电荷变化和更低的能量壁垒。同时,我们也探究了不同浓度的Zn~(2+)离子掺杂对稀土掺杂氟化物纳米晶上转换发光的影响,实现了稀土掺杂的氟化物纳米晶上转换发光强度的提高。采用均相沉淀法制备了Y(OH)_3@Y(OH)_3核壳结构微球,经1100℃焙烧后制备出具有上转换发光性质的Yb~(3+)-Tm~(3+)-Gd~(3+)共掺的Y_2O_3的纳米晶体,讨论了Yb~(3+)-Tm~(3+)-Gd~(3+)在Y_2O_3中能量传递过程及壳层对发光强度的影响。TEM和XRD结果证明了通过焙烧后合成了Y_2O_3核壳结构。上转换光谱结果表明,在Yb~(3+)-Tm~(3+)-Gd~(3+)共掺体系中,核壳结构大幅度提高了Tm~(3+)和Gd~(3+)的上转换荧光强度,尤其是310 nm附近的紫外发光部分增强更为明显。同时,通过研究Tm~(3+)和Gd~(3+)在不同波段的发光强度与泵浦功率的关系探讨了上转换发光的机制。采用均相沉淀法合成了Gd(OH)_3@Gd(OH)_3核壳结构微球,经1100℃焙烧后制备出具有上转换发光性质的Yb~(3+)-Er~(3+)/Tm~(3+)共掺的Gd_2O_3的纳米晶体。在980 nm激发光激发下,通过包覆同质壳层,观察到Gd_2O_3@Gd_2O_3纳米晶中Er~(3+)(Tm~(3+))离子上转换发光强度的大幅度增强。同时,在实验结果的基础上讨论了稀土离子间能量吸收和能量传递过程。采用本体聚合法合成了NaYF_4/PMMA复合材料,掺杂Er~(3+)的NaYF_4纳米晶均匀分布在PMMA聚合物中。稀土纳米粒子的掺杂提高了PMMA复合材料的耐热性,而复合材料透光性没有明显地降低。在980 nm激发光条件下,复合材料发射出明显的绿光,同时,随着NaYF_4纳米粒子掺杂含量的提高,复合材料的上转换发光强度逐渐提高。
[Abstract]:Lanthanide doped nanocrystals have unique optical properties and have many potential applications in imaging in vivo, solar cells and 3D display. In particular, oxide and fluoride nanocrystals are often used as main lattice materials for nanocrystalline because of their unique optical properties, high chemical stability and low energy. The composite of rare earth nanocrystalline and polymer will further promote the wide application of rare earth nanocrystalline. YF_3 nanocrystals, 伪 -NaYF4 and 尾 -NaYF4 mixed nanocrystals and 尾 -NaYF4 nanocrystals have been successfully synthesized by hydrothermal method. By adding Zn~(2) ions into the synthesized fluoride nanoparticles and changing the concentration of Zn~(2) ions, the process of phase transition from YF_3 to 伪 -NaYF4 nanocrystals and 伪 -NaYF4 to 尾 -NaYF4 nanocrystals was realized. The phase transition is mainly due to the fact that the lattice sites of the Zn~(2) ions replace YP3) ions leading to the change of charge and lower energy barriers. We also investigated the effect of different concentrations of Zn~(2 ion doping on upconversion luminescence of rare earth doped fluoride nanocrystals. The upconversion luminescence intensity of rare earth doped fluorides nanocrystals was improved. YOHHHX 3DX O HH3 codoped Y2O3 nanocrystals were prepared by homogeneous precipitation method. The codoped Y2O3 nanocrystals were prepared by calcination at 1100 鈩，

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