【作者】 张蕾；

【导师】 张翠妙；

【作者基本信息】 河北大学 ， 物理化学， 2020， 硕士

【摘要】 无机固体发光材料具有结构稳定、原料易得等优势,被广泛应用到照明、信息显示以及医学诊断等领域。其中,稀土发光材料因其具有特殊的电子层结构而展现出其他发光材料无可比拟的优点,这种优异发光特性为其作为高效发光材料奠定了基础。因此,寻找声子能量低、量子效率高、物理化学稳定性高的新材料作为发光基质成为科研工作者的研究热点。本文通过溶胶-凝胶法、静电纺丝法制备了一系列稀土离子掺杂硅酸铋(Bi₄Si₃O₁₂)发光材料,并对材料的物相结构、形貌特征、形成过程及光谱特性做了详细研究。主要工作内容如下:以柠檬酸作为络合剂、水为溶剂,采用Pechini溶胶-凝胶法合成了纯Bi₄Si₃O₁₂,研究了其结构以及光谱特性,通过掺杂稀土上转换离子合成了新型Bi₄Si₃O₁₂:Yb³⁺/Ln³⁺（Ln=Er,Tm,Ho）上转换荧光粉,在近红外光激发下,Bi₄Si₃O₁₂:Yb³⁺/Er³⁺、Bi₄Si₃O₁₂:Yb³⁺/Tm³⁺和Bi₄Si₃O₁₂:Yb³⁺/Ho³⁺样品分别表现出强烈的绿色、蓝色和红色发射,表明Bi₄Si₃O₁₂为优质的荧光基质材料。研究了其光谱特性与器件应用,通过将合成的荧光粉涂覆在940nm的近红外芯片上,制备了发光二极管（LED）器件。所得的LED器件呈现明亮的多色发射,表明所合成的材料在固态照明和电子显示等方面具有潜在应用前景。采用Pechini溶胶-凝胶法合成了稀土下转换硅酸铋发光材料Bi₄Si₃O₁₂:Ln³⁺（Ln=Sm,Dy,Eu）,由于Bi³⁺存在,基质在462 nm吸收紫外辐射并发出强烈的蓝绿色发射。合成的单相荧光粉表现出Bi₄Si₃O₁₂基质固有的宽频带发射和Ln³⁺离子特有的尖峰发射,通过调节Ln³⁺掺杂浓度可以在单相荧光粉中产生包括白光在内的颜色可调的多色发射。将白色单相荧光粉与280 nm紫外LED芯片复合可表现出明亮的白光发射,表明制备的单相白光荧光粉在WLED市场上具有光明的应用前景。利用简单、高效的静电纺丝技术首次制备出Bi₄Si₃O₁₂一维纳米纤维。在合成过程中,详细研究了不同质量比的添加剂PVP/PEO与煅烧温度对样品形貌的影响,同时对荧光材料的光谱特性及荧光效率等性质进行了研究。该发光材料有潜力作为新型高效节能环保发光材料,在光电器件和光学显示等领域体现其潜在的应用价值。更多还原

【Abstract】 In recent years,inorganic solid luminescent materials have been widely used in lighting,information displays,and medical diagnosis due to their stable structure and easy availability of raw materials.Among them,rare earth luminescent materials exhibit some advantages in comparison with other luminescent materials due to their special electronic layer structure,which lays a foundation for the production of efficient luminescent materials.Therefore,it has become a research hotspot for exploring new materials with low phonon energy,high quantum efficiency,and high physicochemical stability as luminescent host.In this paper,a series of bismuth silicate(Bi₄Si₃O₁₂)luminescent materials have been prepared by sol-gel method and electrostatic spinning method.The main contents are as follows:The novel bismuth silicate Bi₄Si₃O₁₂:Yb³⁺/Ln³⁺（Ln=Er,Tm,Ho）up-conversion（UC）phosphors have been synthesized via a simple sol-gel approach with sodium citrate as complexing agent and water as solvent.Under NIR light excitation,the Yb³⁺/Er³⁺,Yb³⁺/Tm³⁺,and Yb³⁺/Ho³⁺-doped Bi₄Si₃O₁₂2 samples exhibit intense green,blue,and red emissions,respectively.The light-emitting diode（LED）devices have been fabricated by coating the as-synthesized phosphors into 940 nm NIR chips.The as-obtained LED devices can emit visible multicolor emissions under an injection current,which indicates that Bi₄Si₃O₁₂:Yb³⁺/Ln³⁺（Ln=Er,Tm,and Ho）UC luminescent materials may be potentially applied in solid state lighting.A series of down-conversion（DC）lanthanide activator ions（Ln=Sm,Dy,Eu）doped bismuth silicate Bi₄Si₃O₁₂2 phosphors have been synthesized by a sol-gel route.The Bi₄Si₃O₁₂host exhibits intense green-blue emission which are due to the existence of Bi³⁺ions.The as-synthesized Bi₄Si₃O₁₂:Ln³⁺phosphors show both the intrinsic broad band luminescence of Bi₄Si₃O₁₂2 host and the characteristic sharp peak emissions of Ln³⁺ions,which can generate the tunable multicolor emissions in a single-phase phosphor by adjusting the Ln³⁺doping concentrations.By integrating the Bi₄Si₃O₁₂:Ln³⁺phosphors into a 280 nm UV LED chip,all the fabricated WLED devices can exhibit bright white light emission,which provides direct evidence that the as-synthesized BSO:Ln³⁺（Ln=Sm,Dy,and Eu）single-phase white-emitting phosphors have great potential for WLEDs and optoelectronic devices.A series of novel one-dimensional bismuth silicate(Bi₄Si₃O₁₂)fibers have been synthesized via electrospinning method followed by a subsequent annealing process for the first time.During the synthesis process,the mass ratio of PVP/PEO additives plays a crucial role for the formation of the uniform and well-dispersed fibrous precursors.Due to the good crystallinity,uniform fibrous morphology,and eminent DC and UC luminescence properties,the as-synthesized Ln³⁺doped Bi₄Si₃O₁₂2 fibers may find potential applications in fields of optoelectronic devices and solid state lightening.更多还原