【作者】 余雪；

【导师】 王育华；

【作者基本信息】 兰州大学 ， 材料物理与化学， 2010， 博士

【摘要】 纳米发光材料在真空紫外(VUV)激发下具有独特的光学特性,并且能够为显示技术分辨率的提高及器件小型化的发展提供可能。本论文主要采用水热法制备了真空紫外用纳米绿色发光材料：Mn2+离子掺杂的硅酸盐和稀土离子掺杂的氟化物。一方面,对传统的硅酸锌掺锰绿色发光材料进行了纳米级别的优化设计,并研究了其在真空紫外激发下的独特光学性能；另一方面,选择、设计并研究了新型氟化物纳米绿色发光材料。论文主要内容有：1.采用水热合成方法,以正硅酸乙酯(TEOS)作为硅源,在较低反应温度下合成了纯六方相结构的纳米Zn2SiO4：Mn2+发光材料,其合成温度(140℃)是已见文献报道中最低的。对所合成发光材料的性能研究表明,在真空紫外光激发下,纳米Zn2SiO4：Mn2+具有良好的绿光发射,其发射光谱是处于525 nm的宽带峰；通过表面活性剂的添加,可以制备不同形貌的Zn2SiO4：Mn2+发光材料。具有规则形貌的球形Zn2SiO4：Mn2+具有更高的发射强度。在制备得到的不同颗粒尺寸的系列球形Zn2-xSiO4：xMn2+纳米颗粒中,由于纳米材料的尺寸效应,在VUV激发下,随着颗粒尺度的减小,系列样品具的猝灭浓度提高,Mn2+离子的衰减时间变长。2.热处理和共掺杂其它离子能够有效改善水热得到的Zn2SiO4：Mn2+样品的光学性能。热处理后,纳米Zn2SiO4：Mn2+保持了其规则球形形貌,且发光强度明显增强,达到商用Zn2SiO4：Mn2+荧光粉的86%。这是由于热处理使得纳米颗粒的结晶性能提高,其表面缺陷减少,从而无辐射跃迁几率减少,发光强度提高。但是与热处理前样品比较发现其余辉时间增长。为了进一步改善纳米Zn2SiO4：Mn2+的余辉时间,在纳米Zn2SiO4：Mn2+的样品中共掺杂了其他金属离子,结果发现,适当的Mg2+离子掺杂,可使Zn2SiO4：Mn2+纳米颗粒的衰减时间缩短至4.98 ms；Ca2+离子掺杂的纳米Zn2SiO4：Mn2+颗粒的发光强度达到商用粉的107%。通过分析,认为共掺杂离子引起了纳米Zn2SiO4：Mn2+的晶格畸变,使得双重禁戒的Mn2+离子跃迁放宽,从而改善了纳米Zn2SiO4：Mn2+的发光强度以及余辉时间。3.水热法合成了六方相纳米NaYF4：Tb3+发光材料,得到的纳米NaYF4：Tb3+粒度均匀,分散性好。随着还原温度的升高,NaYF4的相结构逐渐由六方相转变成立方相。立方相纳米NaYF4：Tb3+在真空紫外下具有良好的绿光发射,立方相的NaYF4：Ce3+能够吸收到的紫外光的能量并将传递给Tb3+离子,使其在紫外区域的绿光发射强度明显提高。而六方相的纳米NaYF4：Ln3+(Ln=Sm,Dy)在真空紫外和紫外光激发下,表现了良好的发光性质。更多还原

【Abstract】 For advancing display device technology, fine particle phosphors which have smaller particle size and more uniform particle shape than those present commercial phosphors are required. In this paper, we synthesized manganese doped silicate and rare earth doped fluoride nano-phosphor via hydrothermal route. The main work focused on the improvement of photoluminescence (PL) properties of traditional Zn2SiO4:Mn2+ phosphor in nano scale. In addition, the unique PL properties of nano phosphor under vacuum ultraviolet (VUV) excitation were also discussed. On the other hand, the VUV PL properties of rare earth doped fluoride nanophosphors were selected and studied.1.Nanoscaled hexagonal Zn2SiO4:Mn2+ green phosphor with regular and uniform morphology was synthesized by hydrothermal method at a low temperature of 140℃, which was the lowest synthesize temperature that ever reported. The as-synthesized nanophosphor exhibited intensive broad emission around 523nm, which was attributed to the 4T1-6A1 transition of Mn2+. When the cetyltrimethyl ammonium bromide (CTAB) as the surfactant molecules was adopted into the hydrothermal procedure, the morphology and the particle size of the phosphor could be controlled. The uniform spherical nanoparticles exhibited the strongest broad emission. Series of Zn2-xSiO4:xMn2+ nanophosphors with different particle size were producted when the condition of the hydrothermal changed. It was found that the highest concentration quenching occurred in the series of Zn2-xSiO4:xMn2+ nanophosphor with the smallest particle size, and the decay time of Mn2+ prolongered with the decrease of particle size due to size effect in nano-materials.2. Heat-treatment and codoping other ions could improve the PL properties of the hydrothermal production. After the heat-treatment, PL intensity of the Zn2SiO4:Mn2+ nanophosphor increased along with the elongered decay time, while still keeping the monodispersed spherical morplogy. The decay time of Mg2+ codoped Zn2SiO4:Mn2+ is 4.981 ms, is much shorter than the commercial bulk phosphor. The PL intensity of Zn2SiO4:Mn2+,Ca2+ nanophosphor was 107% of that of commercial bulk phosphor.3.Hexagonal NaYF4:Tb3+ nanophosphor with well dispersed morphology was synthesized by the hydrothermal route. With the increasing reduction temperature, the hexagonal NaYF4 (β-NaYF4) was gradually replaced by cubic NaYF4(a-NaYF4). Tb3+ doped cubic NaYF4 exhibited intensive green PL under VUV or ultraviolet (UV) excitation. The green emission of Tb3+ in cubic NaYF4 was obviously improved with Ce3+ codoped due to the energy transfer procedure under UV excitation. Nano Hexagonal NaYF4:Ln3+(Ln=Sm, Dy) exhibit excellent PL properties under VUV or UV excitation.更多还原