【作者】 谭淑媛；

【导师】 景晓燕；

【作者基本信息】 哈尔滨工程大学 ， 材料学， 2010， 博士

【摘要】 本论文首先针对NaYF4这种上转换发光材料,通过表面包覆的方法合成了一种核-壳结构的纳米复合发光材料。采用溶胶-凝胶法为主要实验方法,在二氧化硅粒子表面包覆NaYF4:Yb3+/Er3+(或Yb3+/Tm3+)荧光粉层,制备了一系列NaYF4体系稀土离子(Yb3+,Er3+/Tm3+)掺杂的核-壳结构发光材料,解决了直接合成球形纳米发光材料的难题。与其他方法相比溶胶-凝胶法具有工艺简单、易于操作和不需要复杂的设备等优点。然后,采用两部喷雾热解法合成了Pr3+掺杂的CaTiO3球形荧光粉粒子,实验中使用柠檬酸和聚乙二醇(PEG)作为添加剂。最后,采用简单的溶剂热法合成了稀土离子Eu3+、Sm3+和Dy3+掺杂的CaWO4荧光粉纳米粒子和稀土离子Eu3+、Tb3+和Dy3+掺杂的SrMoO4荧光粉纳米粒子。上述材料的结构、形貌和光学性质分别通过X射线衍射(XRD)、傅立叶变换红外光谱(FT-IR)、场发射扫描电镜(SEM)、透射电镜(TEM)、X光电子能谱分析(XPS)和光致发光光谱(PL)等手段来表征。结果表明,制备的NaYF4:Ln@SiO2 (Ln=Yb/Er, Yb/Tm)和NaYF4:Ln@MCM-41 (Ln=Yb/Er, Yb/Tm)样品为核-壳结构。其中未煅烧样品为α-NaYF4单一相：400℃以上煅烧后,α-NaYF4与β-NaYF4共存,且β-NaYF4为主相。包覆的粒子呈均匀球形结构,单分散性好,粒径约为300nm。包覆的NaYF4:Ln壳层致密均匀,并且光滑、无开裂,厚度约为30nm,晶格间距为0.29nm,与NaYF4的XRD谱图(101)的d值符合的很好,说明了NaYF4:Ln(Ln= Yb/Er, Yb/Tm)在Si02表面结晶完好。在980nm红外光激发下,材料呈现明亮的上转换发光。合成的CaTiO3:Pr3+荧光粉是亚微米级球形粒子。325 nm紫外光激发和低压电子束(1-5 kV)作用下粒子显示出Pr3+的强1D2-3H4(612 nm)红光发射。此外,CaTiO3:Pr3+粒子的形态、PL和CL强度可通过改变PEG的浓度、焙烧温度和加速电压进行调节。这种荧光粉粒子在场发射平板显示器方面存在广阔的应用前景。制备的CaWO4:Ln (Ln=Eu3+、Sm3+和Dy3+)荧光粉具有CaWO4相的白钨矿结构,并且是由窄粒径分布、分散性良好的纳米晶体组成的。在紫外光激发或低压电子束作用下,CaWO4:Eu3+、CaWO4:Sm3+和CaWO4:Dy3+荧光粉分别显示Eu3+的5D0-7F1-3特征发射峰、Sm3+的4G5/2-6H5/29/2特征发射峰和Dy3+的4F9/2-6H13/2-15/2特征发射峰。这种荧光粉在荧光灯、场发射显示器和生物标签等方面具有应用前景。稀土离子Eu3+、Tb3+和Dy3+掺杂的SrMoO4粒子形态均一,是由简单的溶剂热法制备所得。XRD结果表明三种掺杂样品都具有高纯度和高结晶度。SrMoO4:Ln (Ln=Eu3+、Tb3+和Dy3+)样品呈现相当均匀的花生状和椭球状粒子。紫外光激发下,SrMoO4:Eu3+、SrMoO4:Tb3+和SrMoO4:Dy3+荧光粉分别显示Eu3+的5D0-7F1-3特征发射峰、Tb3+的5D4-7F3-6特征发射峰和Dy3+的4F9/2-6H13/2-15/2特征发射峰。这种荧光粉在荧光灯和发光二极管方面具有很高的应用潜力。更多还原

【Abstract】 In this thesis, firstly, the core-shell structure of a kind of up-conversion phosphor material NaYF4 had been synthesized by coating. Using the inorganic silica sphere as cores resolved the problem of preparing directly the spherical nanocomposites. A simple sol-gel process has been developed to coat NaYF4:Yb3+/Er3+(or Yb3+/Tm3+) phosphor layers on monodisperse spherical SiO2 particles. Compared with other preparation methods, sol-gel method has the advantages as follows:simple procedure, easy operation, nocomplic-ated instruments. Secondly, spherical Pr3+ doped CaTiO3 phosphor particles were fabricated through a two-step spray pyrolysis process, using citric acid and polyethylene glycol (PEG) as additives. Finally, Rare earth ions (Eu3+, Sm3+, Dy3+) doped CaWO4 nanoparticles and rare earth ions (Eu3+, Tb3+, Dy3+) doped SrMoO4 nanoparticles were synthesized via a facile solvothermal process.The structure, morphology, textural and optical properties were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence spectra (PL), respectively.The results show that the core-shell structure phosphors NaYF4:Yb,Er/Tm@Si02 and NaYF4:Yb,Er/Tm@MCM-41 without annealing showed a cubic spinel structure of a-NaYF4. After being annealed above 400℃, the coexistence of a cubic and hexagonal structure of NaYF4 was obtained. The obtained core-shell structured phosphors maintain spherical morphology, submicrometer size and narrow size distribution, which have an average diameter of 300nm. Furthermore, uniform, smooth and crack-free phosphor films with thickness of 30nm were obtained. TEM results showed that the lattice fringes obvious and the distance between the adjacent lines are well consistent with the d value of (101) plane of NaYF4. The intense up-conversion emission was observed from the nanocrystals under excitation at 980nm.The as-prepared CaTiO3:Pr3+ phosphors are spherical with submicron particle size. The particles show a strong red emission corresponding to 1D2-3H4 (612 nm) of Pr3+ under the ultraviolet excitation (325 nm) and low voltage electron beams (1-5 kV). Furthermore, the morphology, PL and CL intensities of the CaTiO3:Pr3+ phosphors can be tuned by altering the concentration of PEG, annealing temperature, and acceleration voltage. These phosphors show potential applications in the field of field emission displays (FEDs).The XRD results reveal that all the doped samples are well assigned to the scheelite structure of the CaWO4 phase. The as-made phosphors consist of well-dispersed nanocrystals with relatively narrow size distribution. Upon excitation by ultraviolet radiation or low-voltage electron beams, the CaWO4:Eu3+ phosphors show the characteristic 5D0-7F1-3 emission lines of Eu3+, the CaWO4:Sm3+phosphors exhibit the characteristic 4G5/2-6H5/2-9/2 emission lines of Sm3+, and the CaWO4:Dy3+ phosphors demonstrate the characteristic 4F9/2-6H13/2-15/2 emission lines of Dy3+, respectively. These phosphors show potential applications in the fields of fluorescent lamps, field emission displays and biological labeling.Rare-earth ions(Eu3+、Tb3+ and Dy3+) doped SrMoO4 particles with uniform morphologies were successfully prepared through a facile solvothermal process. The XRD results reveal that all the doped samples are of high purity and crystallinity. It has been shown that the as-synthesized SrMoO4:Ln (Ln=Eu3+、Tb3+ and Dy3+)samples show respective uniform peanut-like and oval morphologies with narrow size distribution. Upon excitation by ultraviolet radiation, the SrMoO4:Eu3+ phosphors show the characteristic 5D0-7F1-3 emission lines of Eu3+, while the SrMoO4:Tb3+ phosphors exhibit the characteristic 5D4-7F3-6 emission lines of Tb3+, and SrMoO4:Dy3+ phosphors exhibit the characteristic 4F9/2-6H13/2-15/2 emission lines of Dy3+. These phosphors exhibit potential applications in the fields of fluorescent lamps and light emitting diodes (LEDs).更多还原