【作者】 杨帆；

【导师】 仲海洋；

【作者基本信息】 大连海事大学 ， 凝聚态物理， 2011， 硕士

【摘要】 作为新世纪固体照明领域的重要组成,白光LED以其节能、环保、高效等诸多优良特性而受到广泛关注。目前技术最成熟的白光LED是由日本公司研发出的蓝光LED芯片涂覆黄色YAG:Ce3+荧光粉合成的。但是由于YAG:Ce3+荧光粉的专利限制以及缺乏红光成分导致显色性低的问题使得对于寻求新型荧光粉的研究变得越来越重要。在最近的研究中,掺杂Eu2+离子的碱土金属硅酸盐由于良好的稳定性、合成工艺简单等优点引起了研究人员的兴趣。本文以此为背景进行了白光LED用硅酸盐荧光粉的研究,取得如下结果：1.利用高温固相法合成不同浓度Eu2+掺杂的Sr2SiO4,研究了不同种类助熔剂对产物晶相结构及发光性能的影响,确定最佳的助熔剂为硼酸。通过激发和发光光谱研究了Eu2+掺杂的Sr2SiO4荧光粉的发光机理、浓度猝灭行为及色度学性质。通过光谱分析得出当Eu2+离子占据不同格位的Sr时其发光性能会有所不同。通过研究不同激发波长激发下的发射光谱以及色坐标得出样品的发光性受激发波长影响很大。样品的色坐标表明,所合成的荧光粉有应用于白光LED领域的可能。2.在还原气氛下,采用高温固相反应合成了SrO-MgO-SiO2:Eu荧光粉材料,研究了不同SiO2含量对产物的晶体结构、形貌、发光性质及色度学性质的影响。结果发现：制备出的荧光粉是由单斜晶系的Sr2SiO4和正交晶系的Mg2(SiO4)两相组成,SiO2的含量不影响样品的晶格结构。通过扫描电镜图片可以看出,SiO2的含量改变基本不影响荧光粉的晶体形貌。当SiO2含量较低时,Eu2+离子和Eu3+离子共同存在于合成的荧光粉当中,其中Eu3+离子占据着基质的晶格间隙中,Eu2+占据着Sr2SiO4化合物中Sr(I)和Sr(Ⅱ)两个格位。当SiO2含量较高时,反应可以更充分的进行且Eu2+掺杂情况好,使得发射强度增强。样品的色坐标位置取决于SiO2的含量以及激发波长。更多还原

【Abstract】 As an important component of solid state lighting field in the new century, white-light emission diode(W-LED) has attracted great attention due to its outstanding advantages such as energy saving, environmental protection and high luminescent efficiency, etc. So far. blue LED chips coated with a yellowish phosphor of YAG:Ce3+ have been invented by Japanese company, which is considered as the most widely used technique. However, developing novel phosphors are becoming more and more important due to patent issue and poor color rendering index caused by lacking of red component in emission spectra. In resent researches, Eu2+ ions doped alkaline earth silicates have been extensively investigated as excellent phosphor used for white LED due to its good properties for chemical and thermal stability, simplesynthesis technology. According to the discussion above, W-LED phosphors have been studied in this paper, and results show as follows:1. Sr2SiO4 phosphors are synthesized with different concentrations of Eu2+ ions through high-temperature solid-state reaction. The influence of different flux on the crystal phase and the luminescent properties of the sample are studied, and the boric acid is adopted as the best flux by analyzing the structure and spectra of samples. The mechanism of luminescence, the quenching concentration and the colorimetric performance are investigated based on the excitation and emission spectra. The Eu2+ ions show different luminescent properties while their occupying different Sr2+ sites by analyzing the spectra of the sample. The luminescent properties of the samples are greatly dependant on the excitation wavelength by analyzing the dependence of emission spectra and color coordinates on the excitation wavelength. The color coordinate of sample shows that the production has a potential application in W-LED field.2. Phosphors with compositions of SrO-MgO-SiO2:Eu are prepared in reducing atmosphere via high-temperature solid-state reaction technique. The impact on crystal structure, morphology, luminescent properties and colorimetric performance of the production are under study with varied SiO2 content. The results show that the phosphors prepared is confirmed to be a mixture of monoclinic Sr2SiO4 and orthorhombic Mg2(Si2O4), while SiO2 content does not affect the crystal structure of the samples. The scanning electron microscope images reveal that SiO2 content does not have any influence on the morphology of phosphors. On one hand, Eu2+ and Eu3+ ions co-existed in the phosphors when the SiO2 content is low, with EuJ3+ ions occupying the clearance of crystal lattice in the matrix and Eu2+ ions occupied two sites of Sr(I) and Sr(II) in compound of Sr2SiO4. On the other hand, with high SiO2 content, the Eu2+ ions can be easily doped into the sample due to the sufficient reaction, giving rise to strong emission intensity. The color coordinates are determined by the content of SiO2 as well as the excitation wavelengths.更多还原