【作者】 万静；

【导师】 程丽红；

【作者基本信息】 大连海事大学 ， 凝聚态物理， 2010， 硕士

【摘要】 近年来,白光LED因具有节能、环保等诸多优势越来越受到人们的广泛关注,逐渐成为未来照明领域的主流产品。实现白光LED的方法有很多,目前比较有发展前景的一种方法是荧光粉光转换法,即用蓝光或近紫外光LED激发荧光粉而发出白光。钼酸根离子能够有效吸收近紫外光,并能将吸收的能量有效地传递给激活剂离子,因此本论文进行了单掺及共掺杂的钼酸钆荧光粉光谱性质的研究,探索其实现白光的可能性。我们采用传统的高温固相反应法分别合成了单掺、共掺以及单掺的钼酸钆荧光粉,通过XRD、SEM、荧光光谱、荧光动力学测试以及色坐标的计算等方法对不同浓度的激活剂离子在钼酸钆基质材料中的发光特性及能量传递行为进行研究。通过对掺杂的钼酸钆荧光粉的发光特性的分析,可知该体系能被近紫外光有效激发,且能量传递效率较高,浓度过高时会发生浓度猝灭现象,这是因为Dy3＋之间发生交叉弛豫现象以及存在电偶极-电偶极相互作用。可发蓝光和黄光,故其有实现白光的可能,但其缺乏红光部分,故其显色性较差。为了补偿单掺的钼酸钆荧光粉的红光成分的缺乏,我们引入作为共掺杂发光中心。通过光谱分析了共掺钼酸钆荧光粉的发光特性,发现在近紫外区域,在Mo-O和之间起传递能量的桥梁作用,的引入增加了Mo-O到的能量传递途径,使能量传递效率更高。掺入一定量的可实现具有一定比例的蓝、黄、红的发射,同时实现红色补偿和白光发射。合成一系列变浓度的单掺的钼酸钆荧光粉,通过分析其激发和发射光谱以及荧光衰减曲线,观察到了之间的两个电偶极相互作用的交叉驰豫过程,而在能级上间的交换相互作用的能量迁移行为没有观察到,这主要是因为在化合物中我们所研究的浓度范围内的间的距离还不够小。同时,通过色坐标的计算发现,样品的发射色坐标随着浓度而变化。更多还原

【Abstract】 In recent years, white light emitting diodes (white-LEDs) have attracted increasing attention because of their energy-saving and environment-friendly features. What’s more, they are gradually playing an important role in the lighting field at present and in the future. The white lights can be obtained via several approaches. Amongst all the approaches the light-converting-phosphor method, namely, converting the blue lights or near ultraviolet lights from GaN-based LEDs into visible lights to form white lights, is considered to be the most promising one. In this thesis, we study on the Dy3+, Tb3+ single-doped and Dy3+/Eu3+ co-doped Gd2(MoO4)3 phosphors with the aim of exploring their feasibilities of practical applications since the MoO42- can effectively absorb the near ultraviolet light and transfer its energy to rare earth ions.Dy3+, Tb3+single-doped, Dy3+/Eu3+ co-doped Gd2(MoO4)3 phosphors were prepared by a conventional high-temperature solid-state reaction method. Their crystal structures, morphology, and spectroscopic properties were characterized by using XRD, SEM, optical spectroscopy and colorimetry, meanwhile, the energy transfers between rare earths and between rare earths and hosts were also studied.Based on the analysis of the spectral properties of Gd2(MoO4)3:Dy3+ phosphors, it was found that these phosphors could be effectively excited with near ultraviolet lights, and the energy transfer from host to Dy3+ is very effective; the energy transfers between Dy3+ ions were also studied in the framework of I-H model. The energy transfer mechanism was attributed to the electric dipole-dipole interaction. The possibility for getting white lights with the phosphors was discussed, and it was found that the red component is of lack in the emission spectra.In order to improve the color rendering property of Dy3+ single-doped Gd2(Mo04)3 phosphors, The Eu3+, which can emit red light, was introduced. It was found that Eu3+ can be an energy transfer bridge between the Dy3+ and Mo-O bond according to the analyses of luminescent properties of Dy3+/Eu3+ co-doped samples. The introduction of Eu3+ can increase the energy transfer efficiency. Moreover, it was also found that the comparable emission intensities for blue, yellow and red emissions and white light emission mixed by them can be achieved by properly adjusting Eu3+ and Dy3+ concentrations.更多还原