【作者】 郭娜；

【导师】 郝霄鹏；

【作者基本信息】 山东大学 ， 材料学， 2010， 硕士

【摘要】 白光发光二极管(WLED)是一种高效、节能、环保、长寿命的新型固态照明技术,被誉为第四代照明光源,也称为21世纪绿色光源。制备WLED主要有两大途径,其中使用发射黄光的无机稀土发光材料与蓝光LED封装组成WLED是近期发展的主要方向。荧光粉技术的进步对WLED的发展有着至关重要的作用。目前用YAG：Ce荧光粉制备的WLED因其发射波长较短,显色指数较小(<80),使其发光颜色偏蓝色,刺激人的眼睛。为了克服这一缺点,我们制备了一种能被蓝光LED(最佳发射波长在465 nm左右)有效激发的橙黄光发射荧光粉。首先,利用溶胶-凝胶低温燃烧法制备了铝酸盐基纳米发光材料MAl2O4：Eu2+,Eu3+(M=Mg,Ca,Sr,Ba),并对其结构、形貌和荧光性质进行了研究。结果表明,在600℃低温下即可得到纯晶相产物,样品中同时出现了Eu2+的4f65d1-4f7发射及Eu3+的f-f发射。通过计算其色度坐标发现,MgAl2O4：Eu2+,Eu3+、CaAl2O4：Eu2+,Eu3+、BaAl2O4：Eu2+,Eu3+三种荧光粉的发光区域均在橙黄光区。其次,为了进一步提高MAl2O4：Eu2+,Eu3+中Eu3+的发射强度,制备了复合碱土铝酸盐MgxM1-xAl2O4:Eu2+,Eu3+(M=Sr,Ca,Ba)荧光粉,同时研究了基质中碱土离子掺杂比例、燃烧温度、燃烧时间、以及Eu3+的掺杂浓度等对产物发光性质的影响。掺入少量碱土离子Mg时,样品先是保持本身晶相(MAl2O4(M=SrCa,Ba))不变,持续增加Mg的含量,样品由一种晶相变为两种晶相(MAl2O4与MgAl2O4)的混合物,最终变为单一晶相(MgAl2O4)。光致发光研究结果表明,低温燃烧(600℃)得到的样品的发光强度较高,燃烧时间对其发光性质几乎没有影响；当对MgAl2O4基质进行10%碱土离子(Sr,Ca,Ba)掺杂后,产物中Eu3+的发光强度得到了明显的提高,与此同时,Eu2+的发光强度基本不变,而且二者发射峰位置并没有发生变化。由色度坐标分析得到, Mg0.9Sr0.1Al2O4：Eu2+,Eu3+发光区域仍在橙黄光区,但Mg0.9Ca0.1IAl2O4：Eu2+, Eu3+与Mg0.9Ba0.1Al2O4：Eu2+,Eu3+二者的发光区域转移到红光区。第三,用同种方法制备了稀土元素共掺杂的Mg0.9Sr0.1Al2O4：Eu2+,Eu3+,Ce3+、Mg0.9Sr0.1Al2O4：Eu2+,Eu3+,Dy3+Mg0.9Sr0.1Al2O4：Eu2+,Eu3+,Pr3+纳米荧光材料,并研究了其晶体结构及发光性质。稀土元素的掺杂没有改变晶体结构,但由于样品基质中陷阱能级的生成及稀土离子间的能量转移,产物中没有发现Ce3+、Dy3+、Pr3+的特征发射。同时,在样品中Eu2+的发光强度基本不变,但Eu3+发光强度明显减弱,且二者发光峰的位置未发生变化,因此,样品发光中红光部分减少。更多还原

【Abstract】 White light-emitting diode (WLED) with lots of excellent properties, such as efficient, energy saving, environmental protection and long lasting lifetime, is a new solid state lighting technology. It is well known as the fourth-generation lighting source and deemed to a green light source for the 21st century. There are two kinds of approaches to achieve white-emitting LEDs, and the current mainstream of the fabrication of WLED is to combine yellow emitting lanthanide luminescence material with blue emitting LED. The progress of phosphor technology plays an essential role in the development of WLED.Currently, the WLED prepared using YAG:Ce phosphor has a shorter emission wavelength and a poor color rendering index (＜80), which leads to the output light partial to blue light, hence it will irritate people’s eyes. In order to overcome the problem, we have prepared a kind of orange-yellow emitting phosphors which can be effectively excited by blue LED (the optimum emission is about 465 nm).Firstly, Eu2+ and Eu3+ co-doped aluminates luminescence nanomaterials MAl2O4:Eu2+, Eu3+ (M=Mg, Ca, Sr, Ba) have been prepared by sol-gel combustion method. We studied the structure, morphology and the luminescence properties of the samples. It shows that we can obtain pure crystalline products at 600℃. There exists emission of both Eu2+ and Eu3+ at the same time in the samples. The luminescence of MgAl2O4:Eu2+, Eu3+, CaAl2O4:Eu2+, Eu3+, BaAl2O4:Eu2+, Eu3+ are both at orange-yellow region, judged by their chromaticity coordinates.Secondly, we have synthesized MgxM1-xAl2O4:Eu2+, Eu3+(M=Sr, Ca, Ba) phosphors in order to enhance the emission of Eu3+ in MAl2O4:Eu2+, Eu3+. We have also investigated the influence of the ratio of two different alkali-earth ions, the combustion temperature, time, and the doping contents of Eu3+ on luminescent property. Mixed with a small amount of Mg ions, the samples maintained their own phase (MAl2O4 (M=Sr, Ca, Ba)). But when kept on increasing the contents of Mg ions, the products became to be the mixture of MAl2O4 and MgAl2O4, and finally, they turned to be MgAl2O4. Photoluminescence spectra indicated that the samples have the strongest emission when the combustion temperature was 600℃and the combustion time has nearly no effect on the luminescence intensities. When the doping content of Sr, Ca, Ba in MgAl2O4 was 10%, the luminous intensity of Eu3+ was significantly enhanced. And at the same time, the luminescence of Eu2+ was nearly the same as the products synthsised before. Moreover, the peak position of both Eu2+ and Eu3+ did not change. The luminescence of Mg0.9Sr0.1Al2O4:Eu2+, Eu3+ are still at orange-yellow region, but that of Mg0.9Ca0.1Al2O4:Eu2+, Eu3+ and Mg0.9Ba0.1Al2O4:Eu2+, Eu3+ have transferred to the red light area.Thirdly, aluminates luminescence nanomaterials co-doped by rare earth elements, such as Mg0.9Sr0.1Al2O4:Eu2+, Eu3+, Ce3+, Mg0.9Sr0.1Al2O4:Eu2+, Eu3+, Dy3+, and Mg0.9Sr0.1Al2O4:Eu2+, Eu3+, Pr3+ were prepared. We have also studied the crystal structure and luminescence properties. The doping of rare earth elements didn’t change the structure of the sample. We have not found the luminescence of Ce3+、Dy3+、Pr3+ because of the trap level in the matrix and energy transfer between rare earth elements. The luminous intensity of Eu2+ was nearly the same as the products synthesised without co-doped rare earth elements. In the meanwhile, the emission intensity of Eu3+ was significantly reduced. However, the potion of emission peaks of both Eu2+ and Eu3+ did not change. Therefore, the output of the red light became decreased.更多还原