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Preparation and Photoluminescent Propertics of Eu3+,Tb3+Activatcd Oxysalt-based Inminescence Materials

Author: ZhangFeng
Tutor: WangYuHua
School: Lanzhou University
Course: Materials Physics and Chemistry
Keywords: PDP VUV Electronic structure YVO4 KMPO4（M=Sr,Ba） Li6Ln（BO3）3(Ln3+=Y3+,Gd3+) Ca9Ln（PO4）7(Ln=Y3+,La3+) Na3GdP2O8
CLC: O482.31
Type: PhD thesis
Year: 2012
Downloads: 241
Quote: 0
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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.

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CLC: > Mathematical sciences and chemical > Physics > Solid State Physics > Solid nature of the > Optical Properties > Luminescence
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