紫外或近紫外光激发的钨酸盐类荧光粉发光性质的研究

发布时间：2018-08-25 19:17

【摘要】：白光发光二极管(LED)具有快响应、长寿命、高效、节能、稳定、环保等一系列优点,在室外大型建筑照明、交通信号灯以及手机屏幕显示等领域有着广泛的应用,被称为新一代固体照明光源。目前合成白光LED的方法主要有以下三种:第一种是用红光、绿光、蓝光三种LED芯片直接组合产生白光,需要生产对应的三种电路,高昂的生产成本不利于其在市场上的普及;第二种是用蓝光芯片涂覆黄光荧光粉产生白光,但是在产生的白光光谱中缺少较为有效的绿光和红光成分;第三种是通过紫外或近紫外芯片与红、绿、蓝三基色荧光粉的组合产生白光,但也面临着颜色再吸收和配比调控的问题;为了克服上述困难,本论文的研究方向主要为:①制备能被紫外或近紫外光有效激发且热稳定性良好的绿光和红光荧光粉;②研制能被近紫外光有效激发的单一基质白光荧光粉。高温固相法由于制备过程简单、样品结晶度高,成为了目前市场上广泛使用的方法。本论文选取化学性质稳定、合成温度较低的钨酸盐为基质,用高温固相法制备了几种白光LED用荧光粉,并且通过J-O理论深入研究了稀土离子发光性质与晶格周围环境的联系。具体内容有:(1)利用高温固相法合成了单掺Tb~（3+）的Li_3Ba_2Y_3(WO_4)_8绿光荧光粉。实验发现,在单掺Tb~（3+）的荧光粉中,当掺杂浓度为x=0.1或者更低时,基质本身会具有一定强度的蓝光发射;之后,基质的蓝光发射会随着Tb~（3+）浓度的增加而降低;荧光粉的发射光谱在绿光区域(550 nm)达到了峰值。另外,变温光谱以及活化能的分析显示,这种荧光粉具备良好的热稳定性。(2)利用高温固相法合成了不同浓度Eu~（3+）掺杂的Li_3Ba_2Y_3(WO_4)_8红光荧光粉。实验发现,在近紫外光394 nm激发下,这种荧光粉会发出很高强度的红光,同时,它还具有很高的色纯度。通过J-O理论的计算,得出Eu~（3+）在这种荧光粉中的跃迁几率较高,所以Li3Ba2Y3-xEux(WO4)8具备了较高的量子效率。我们还得出这种基质本身的折射率为2.21。对Li3Ba2Y3-xEux(WO4)8热稳定性的研究也显示出这种荧光粉具有优异的热稳定性。(3)利用高温固相法合成了Tb~（3+）/Eu~（3+）共掺的Li_3Ba_2Y_3(WO_4)_8白光荧光粉。实验发现,通过利用基质本身的蓝光发射,在Tb~（3+）浓度为x=0.1的基础上,通过引入不同浓度的Eu~（3+）,荧光粉的发光会由绿光逐渐到达白光区域。同时,这种荧光粉具备良好的热稳定性。
[Abstract]:White light-emitting diode (LED) has a series of advantages such as fast response, long life, high efficiency, energy saving, stability, environmental protection and so on. It has a wide range of applications in outdoor large-scale building lighting, traffic lights, mobile phone screen display and other fields. Is called the new generation solid lighting light source. At present, there are three main methods of synthesizing white light LED: first, three kinds of LED chips, red light, green light and blue light, are used to produce white light directly, which need to produce three corresponding circuits. The high production cost is not conducive to its popularity in the market; The second is to coat yellow phosphors with blue chips to produce white light, but there is a lack of more effective green and red components in the resulting white light spectra; the third is to use ultraviolet or near ultraviolet chips with red and green. The combination of blue trichromatic phosphors produces white light, but also faces the problem of color reabsorption and ratio control. The main research direction of this thesis is to prepare a single substrate white phosphor which can be effectively excited by ultraviolet or near ultraviolet light and which has good thermal stability. High temperature solid-state method is widely used in the market because of its simple preparation process and high crystallinity. In this paper, several white LED phosphors were prepared by high temperature solid state method with stable chemical properties and low temperature tungstate as the substrate. The relationship between the luminescence properties of rare earth ions and the surrounding environment of the crystal lattice was studied by J-O theory. The main contents are as follows: (1) Tb~ (3) doped Li_3Ba_2Y_3 (WO_4) 8 green phosphors were synthesized by high temperature solid state method. It is found that in the phosphor doped with Tb~ (3), the blue emission of the substrate will have a certain intensity when the doping concentration is XG 0.1 or lower, and then the blue emission of the substrate will decrease with the increase of Tb~ (3) concentration. The emission spectrum of the phosphor reached its peak in the green region (550 nm). In addition, the analysis of temperature-varying spectra and activation energy shows that the phosphors have good thermal stability. (2) Li_3Ba_2Y_3 (WO_4) -doped Li_3Ba_2Y_3 (WO_4) red phosphors with different concentrations of Eu~ (3) were synthesized by high temperature solid state method. It is found that the phosphor can emit a high intensity of red light under the excitation of near UV 394 nm. At the same time, it also has a high color purity. By J-O theory, it is found that the transition probability of Eu~ (3) in this phosphor is higher, so Li3Ba2Y3-xEux (WO4) 8 has higher quantum efficiency. We have also obtained that the refractive index of the matrix itself is 2.21. The study on the thermal stability of Li3Ba2Y3-xEux (WO4) 8 also showed that the phosphor had excellent thermal stability. (3) the Tb~ (3) / Eu3 co-doped Li_3Ba_2Y_3 (WO_4) 8 white phosphor was synthesized by high temperature solid state method. It is found that the luminescence of the phosphors will gradually reach the white region by introducing different concentrations of Eu~ (3) on the basis of the blue emission of the substrate and the concentration of Tb~ (3) is 0.1. At the same time, the phosphors have good thermal stability.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O482.31;TN312.8

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