【作者】 慈志鹏；

【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】 发光二极管(Light emitting diodes)又称固体光源,具有节能、环保、全固体化、寿命长等优点,是二十一世纪人类解决能源危机的重要途径之一。其中用“荧光粉转换法”制造LED (pc-LED)受到许多国家和研究工作者的高度关注。荧光粉性能的好坏直接影响LED的发展,目前的LED用荧光粉存在两个主要问题,一是蓝光LED用黄粉缺少红色组分,复合白光显色性差;二是紫外LED用三基色粉发光效率低,复合白光亮度低,因此改善现有主流荧光粉性能或开发新型荧光粉是一项有意义的工作。采用高温固相法制备了红粉CaMoO4：Eu3+并进行掺杂(Si,Nb,V,Sr,Tb,Pb等)改性,首次发现当在Mo位置掺入Si、Nb时,发光强度显著提高,分别达到红粉Y2O2S：0.05Eu3+的5.5和4.2倍(λex=393 nm);对与CaMoO4同结构的NaEu(MoO4)2进行Si、Nb的取代,发现其亮度提高到Y2O2S：0.05Eu3+的3.8和3倍(λex=393 nm)。此外两种红粉物理化学性能稳定,无污染,有望取代硫化物应用于紫外LED与采用高温固相法制备了YVO4：Bi3+,M3+(M=Dy,Er)系列样品,首次研究了其在LED应用波长下(>350 nm)的发光性能,发现YVO4：Bi3+,Dy3+样品在365 nm紫外光激发下发射强烈黄光,是一种潜在的紫外LED用黄粉；YVO4：Bi3+,Er3+样品在365nm紫外光激发下发射纯正白光,最佳样品色坐标为(0.33,0.33),从而在单一体系实现白光发射。在YVO4：Bi3+,M3+(M=Dy,Er)体系中掺入P后,其发光强度明显提高,分别提高23%和27%。首次利用高浓度的C02气氛保护Co气氛还原采用高温固相法合成了MCO3(M=Sr,Ba)基荧光粉,发现Sr1-xBaxCO3：Eu2+样品能在紫外-蓝光区有效激发,发光颜色从橙黄到深红可调,可同时适用于蓝光和紫外LED芯片。此外还采用高温固相法首次合成了假板钛矿结构Y2TiO5基荧光粉研究了其发光性能。本论文开展的现有荧光粉的掺杂改性和新型荧光粉的开发研究得到了一系列有益结果,为解决目前LED用荧光粉面临的问题提供了一定的指导作用,为下一步工作的展开提供了一定的实验参数。更多还原

【Abstract】 White light-emitting diodes (LEDs) technique is an important kind of solid-state illumination. In comparison with conventional incandescent and fluorescent lamps, the white LEDs show many advantages such as high luminescent efficiency, long lifetime, environment friendly, which promise significant reductions in power consumption in the 21st century. In the case of lighting, white light can be generated by several different methods. The most commonly method is to combine a phosphor with a GaN LED chip, and this is called as phosphor-conversion method. So the phosphor conversion LEDs light strongly depends on the phosphor whether it can be efficiently excited by blue or UV emission of LEDs chip or not. Now, there are two major problems on the development of phosphors:one is that the yellow phosphor used in blue LEDs has relatively weak emission in the red spectral region, resulting in inaccurate color rendition; the other is that the tricolor phosphors used in UV LEDs have a low emission intensity, resulting in a low luminous efficiency. Therefore, it is a significant work to seek a kind of phosphor with high luminous efficiency and better color reproducibility for blue or UV LEDs.The red phosphors CaMoO4:Eu3+,M(M=Si,Nb,V,Sr,Tb,Pb,etc) were synthesized by solid state reaction. We firstly found that the red emission intensity of the phosphor CaMooO4:Eu3+ was seriously enhanced when Mo6+ was replaced by Si4+ or Nb5+. The optimize emission intensity of Si and Nb co-doping samples is as 5.5 and 4 times high as that of Y2O2S:0.05Eu3+, respectively. In addition, because NaEu(MoO4)2 and CaMoO4 have similar structures, the red phosphors NaEu(Mo1-xMxO4)2 (M=Si,Nb) were also synthesized by solid state reaction. The optimize emission intensity of NaEu(Mo1-xSixO4)2 and NaEu(Mo1-xNbxO4)2 samples reached as 3.8 and 3 times as that of Y2O2S:0.05Eu3+, respectively. It indicated that the two modified red phosphors might be more suitable for the UV-LED than the sulfide phosphor Y2O2S:0.05Eu3+The phosphors YVO4:Bi3+,M3+(M=Dy,Er) were synthesized by solid state reaction, and the photoluminescence proterties under>350 nm excitation were firstly studied. Under 365 nm excitation, the sample YVO4:Bi3+,Dy3+ emitted yellow light, and the sample YVO4:Bi3+,Er3+ emitted white light. When V was replaced by P, the emission intensity of YVO4:Bi3+,Dy3+ and YVO4:Bi3+,Er3+ samples is seriously enhanced, stepping up 23% and 27% than that of original samples, respectively.The phosphors Sr1-xBaxCO3:Eu2+ were firstly synthesized by the modified solid-state reaction in a reducing atmosphere of CO/CO2 and showed excellent luminescent properties. The excitation spectra cover the range from the near-UV to the visible part, and the emission spectra show a strong emission from the orange to the red part. The results implied that the color-adjustable phosphors can match well with the blue or UV LEDs, which means that the phosphor could be regarded as a potential candidate for the phosphor-converted white LEDs.In addition, we also synthesized the titanate Y2TiO5 host phosphor and researched the photoluminescence properties.更多还原