【作者】 张凤；

【导师】 王育华；

【作者基本信息】 兰州大学 ， 材料物理与化学， 2012， 博士

【摘要】 等离子平板显示(PDP)具有薄、轻、视角广、大画面尺寸、响应速度快、对比度高、色彩饱和度高等诸多优点,其中超快的响应速度使其在三维(3D)显示、高清晰显示上具有较强的优势。真空紫外发光材料作为PDP的重要组成部分,其发光效率、色纯度、衰减时间、稳定性等直接影响到显示的质量。目前,现有的真空紫外发光材料无法满足高性能显示的要求,另一方面,真空紫外发光机理尚不清楚,无法为新型高效真空紫外发光材料的开发提供依据,从而使开发新材料具有一定的盲目性。针对以上问题,本论文通过选取几组含氧酸盐基质材料作为研究对象,系统研究了Eu3+、Tb3+在其中的光致发光特性,探索真空紫外发光性能的影响因素,为真空紫外发光机理的完善提供依据,并探讨其作为PDP用真空紫外发光材料的潜能。主要内容包括以下几方面：1.采用低温水热法,合成了YVO4：Eu3+纳米晶粉末并将La3+成功地掺入到YVO4：Eu3+纳米晶中,通过对比YVO4：Eu3+块体样品与YVO4：Eu3+纳米晶粉末的真空紫外和紫外发光性能,观察到纳米晶粉末的特殊发光特性,另外,研究发现,YVO4：Eu3+纳米晶粉末掺杂La3+后,其在紫外和真空紫外激发下发光亮度均得到提高,并对增强真空紫外发光亮度这一现象的可能原因进行了分析。2.采用固相法合成了KMPO4:Eu3+(M=Sr, Ba)和KSrPO4:Tb3+,并研究了其发光特性。结果表明KMPO4:Eu3+(M=Sr, Ba)在近紫外激发下具有较强的红光发射,另外,发现在相同Eu3+掺杂浓度下,KBaPO4:Eu3+的O2--Eu3+的电荷迁移能要高于KSrPO4:Eu3+的O2--Eu3+的电荷迁移能,电子结构分析表明价带电子的束缚强度是引起电荷跃迁能不同的一个原因；通过对KSrPO4:Tb3+的光学特性分析,对其激发光谱进行了鉴定。3.通过对Eu3+、Tb3+掺杂Li6Ln(BO3)3(Ln3+=Y3+, Gd3+)的紫外及真空紫外光学性能的研究表明,Li6Ln(BO3)3:Eu3+或Tb3+(Ln3+=Y3+,Gd3+)在紫外激发下具有较高猝灭浓度,分析表明发光中心的猝灭为最近邻离子间的能量转移所引起,在真空紫外激发下,由于Gd参与到能量吸收及传递过程中,Li6Gd(BO3)3：Eu3+(或Tb3+)与Li6Y(BO3)3：Eu3+(或Tb3+)相比具有更高的发光效率。4.通过研究Ca9Ln1-x(PO4)7：xTb3+(Ln3+=Y3+,La3+,Gd3+)(0≤x≤1)系列样品在真空紫外光激发下的发光特性,发现在147nm激发下,随着Tb3+离子浓度的增加,样品的发光颜色由蓝光区通过白光区最后至黄绿光区；研究发现Ca9Ln1-x(PO4)7：xTb3+(Ln3+=Y3+,La3+,Gd3+)和Ca9Tb(PO4)7存在量子剪裁现象,另外,在相同Tb3+离子浓度的情况下,额外量子效率存在η(Ca9Y(PO4)7：Tb3+)>η(Ca9Gd(PO4)7：Tb3+)>η(Ca9La(P04)7：Tb3+)的关系。5.通过研究不同稀土离子Ce3+,Tb3+,Dy3+,Eu3+,Sm3+在Na3GdP2O8中真空紫外区的发光特性,确定了基质吸收带,并表明在真空紫外激发下,Gd3+与稀土离子间存在能量传递。另外,通过研究系列Tb3+掺杂Na3GdP2O8的发光特性,对其结构与发光性能的关系进行了分析。上述发光材料中,Ca9Ln(PO4)7：Tb3+(Ln=Y3+,La3+,Gd3+)和Na3GdP2O8：Tb3+在真空紫外激发下具有较短的衰减时间和较高的发光亮度,可作为潜在的真空紫外绿光发射发光材料。更多还原

【Abstract】 Plasma display panels (PDPs) have many merits such as a thin panel, a slight weight, an extensive visual angle, a large screen size, high-speed response with emissive, high contrast, more saturated colors etc. Among these merits, the characteristics of higher response speed lead to the advantage of PDPs for using in3D and high definition displays. Vacuum ultraviolet (VUV) luminescent materials are important components of PDPs and their characteristics such as luminescence efficiency, color purity, decay time and stability play important role on the quality of displays. Up to now, the presently used VUV phosphors can not reach the demand for high-quality displays, on the other hand, the VUV luminescence mechanism is still not clear and it can not supply foundation for exploring novel VUV phosphors with high efficiency, which leads to the blindness for developing new VUV phosphors. Based on these reasons, the photoluminescence of Eu3+and Tb3+activated some groups of oxysalts are investigated, and the factors influencing the properties of VUV phosphors are explored. Then, the potential applications for PDPs are analyzed. The main points are listed below:1. YVO4:Eu3+nanocrystalline powders have been synthesized and La3+has been successfully introduced in YVO4:Eu3+by a mild hydrothermal method. By comparing the photoluminescence of bulk YVO4:Eu3+and nanosized YVO4:Eu3+under UV and VUV excitation, the unusual photoluminescence properties of YVO4:Eu3+nanocrystalline powders have been observed. In addition, the La3+doping sample can be excited more efficiently under both UV and VUV excitations and the possible reason for the enhanced VUV photoluminescence intensity is analyzed.2. KMPO4:Eu3+(M=Sr,Ba) and KSrPO4:Tb3+phosphors have been successfully synthesized by a solid reaction method and their photoluminescence properties have been studied. The results indicate KMPO4:Eu3+(M=Sr, Ba) can be effectively excited by NUV light. In addition, it was found that the position of O2--Eu3+CTB is located at lower energy for KSr0.99PO4:Eu3+0.01than that of KBa0.99PO4:Eu3+0.01. By analyzing the valence band structures, it shows the strength of binding of valence band electrons is a reason for the different locations of O2--Eu3+CTB; the compositions of the excitation spectrum of KSrPO4:Tb3+are deduced by the spectrum analysis. 3. The photoluminescence properties of Eu3+or Tb3+activated Li6Ln(BO3)3(Ln3+=Y3+, Gd3+) under UV and VUV excitations have been investigated. The results indicate that the phosphors Eu3+or Tb3+activated Li6Ln(BO3)3(Ln3+=Y3+,Gd3+) have high quenching concentration and the concentration quenching is caused by the energy transfer among the nearest-neighbor ions. And it can be observed that Li6Gd(BO3)3:Eu3+(or Tb3+) has much more luminescence intensity than that of Li6Y(BO3)3:Eu3+(or Tb3+) due to the role of Gd33+.4. By investigating the VUV photoluminescence properties of a series of Ca9Ln1-x(PO4)7:xTb3+(Ln3+=Y3+, La3+,Gd3+)(0≤x≤1), it can be found the emitting colors of these materials can range from blue to yellowish-green via white by increasing the concentrations of Tb3+under147nm light excitation; visible quantum cutting have been demonstrated in Ca9Ln1-x(PO4)7:xTb3+(Ln3+=Y3+, La3+, Gd3+) and Ca9Tb(PO4)7. The extra quantum efficiency has the following relationship:η(Ca9Y(PO4)7:Tb3+)> η(Ca9Gd(PO4)7:Tb3+)>η(Ca9La(PO4)7:Tb3+) at the same Tb3+concentration.5. The photoluminescence properties of RE3+-activated monoclinic Na3GdP2O8phosphors (RE3+=Tb3+, Dy3+, Eu3+, Sm3+) in the vacuum ultraviolet (VUV) region were investigated. The host absorption band has been determined and an efficient energy transfer from Gd3+to RE3+can be observed under VUV light excitation. In addition, the structure dependent photoluminescence properties have been discussed by investigating a series of Tb3+-activated Na3GdP2O8.Among these materials, Ca9Ln(PO4)7:Tb3+(Ln=Y3+, La3+, Gd3+) and Na3GdP2O8:Tb3+show a shorter decay time and a comparable brightness when compared with the commercial Zn2SiO4:Mn2+green phosphor. These results demonstrate that they are potential green phosphors candidates for plasma display panel applications.更多还原