【作者】 何玲；

【导师】 王育华；

【作者基本信息】 兰州大学 ， 材料物理与化学， 2007， 博士

【摘要】 等离子显示器商用红色荧光粉（Y,Gd）BO₃：Eu³⁺的色纯度不太理想，主要是它的发射偏离了红色更加接近橙色。然而，由于它在真空紫外区的发光强度比其它荧光粉高，它仍是最常用的等离子显示器红粉。理想的等离子显示器用红色荧光粉不但应该有高的发射强度同时也要具备好的色纯度，因此对现有商用红色荧光粉的性能进行改善或开发出性能更好的红色荧光粉是当前研究的主要途径。本论文一方面对现有红色荧光粉进行改性研究，另外一个方面选取有发展潜力的硼酸盐材料作为基质，进行新型红色荧光粉的开发研究。改善荧光粉性能的重要手段之一是选择合适的合成路径，通过控制粉体的表面形态来改善其发光性能。本论文探索了两种软化学合成法—溶胶-凝胶法和水热法在等离子显示器用红色荧光粉合成中的应用并研究了这两种方法对荧光粉发光性能的影响。在远远低于固相反应的温度下，用溶胶-凝胶法和水热法可以成功地合成商用红色荧光粉（Y，Gd）BO₃：Eu³⁺，结果表明用溶胶-凝胶法制备的荧光粉具有较小的粒度和类球形形貌，发光强度高于固相反应，但是主要发射仍然是橙色发射，因此溶胶-凝胶法有利于提高（Y，Gd）BO₃：Eu³⁺荧光粉的发光强度，但是没有根本改变它的色纯度。在采用温和的水热法成功制备出的玫瑰花形、片状、线状和球形等不同形貌的（Y，Gd）BO₃：Eu³⁺中，球形形貌的样品发光强度最好，当Eu³⁺的掺杂浓度高于15mol％时，荧光粉在626nm的红色发射在光谱中占据主导地位。与商用红粉相比，用水热法合成的球形（Y，Gd）BO₃：Eu³荧光粉不但具有较高的发光强度，更重要的是色纯度也得到了根本改善。在开发新型红色荧光粉的研究中，基质的选择非常重要，发光基质的一些性质会在一定程度上直接或者间接的对掺杂离子的发光产生影响，使它的发光特性有所差异。我们选取在真空紫外激发下具有良好吸收的硼酸盐基质作为新型红色荧光粉开发的研究对象，合成了以Eu³⁺离子作为激活离子，以Ca₄GdO（BO₃）₄，Sr₃Y₂（BO₃）₄，BaZr（BO₃）₂，BaB₈O₁₃和Gd₂MoB₂O₉等为基质的多种新型红色荧光粉，并研究了它们在真空紫外—紫外可见光区域内的发光特性。研究发现新型红色荧光材料Ca₄GdO（BO₃）₃：Eu³⁺和Sr₃Y₂（BO₃）₄：Eu³⁺的发射都以纯红色为主，色纯度可以满足等离子显示器荧光粉的要求，但是它们在真空紫外激发下的发光强度不理想，掺杂Al³⁺和La³⁺后，两者的发光强度都有显著提高。BaZr（BO₃）₂：Eu³⁺荧光粉在真空紫外区除了硼氧基团的吸收，还存在Ba-O基团和Zr-O基团的吸收，该荧光粉在真空紫外激发下发光效率较高，但是其主要发射是橙色发射，所以BaZr（BO₃）₂：Eu³⁺作为一种新型的红色荧光粉在显示器件中的应用受到限制。通过掺杂发现，Si⁴⁺离子和Al³⁺对BaZr（BO₃）₂：Eu³⁺的发光有敏化作用，而Gd³⁺与Ti⁴⁺离子对发光有猝灭作用，分析认为这种现象与掺杂离子引入后，荧光粉内部的缺陷有关。对Ba_1-xEu_xB₈O₁₃（0=x=0.2）系列样品发光性质的研究表明BaB₈O₁₃：Eu中的两个发光中心(Eu³⁺和Eu²⁺)之间既存在竞争发射也有发光中心之间的共振能量传递。用高温固相法合成的新型红色Gd₂MoB₂O₉：Eu³⁺荧光粉在真空紫外激发下发光效率是当前商用红粉（Y，Gd）BO₃：Eu³⁺的85％，并且其发射以626nm的红色发射为主。在Gd₂MoB₂O₉：Eu³⁺中分别掺杂Y³⁺，Al³⁺和La³⁺之后，发光强度都有明显提高，其中Y³⁺对发光的敏化效果最好。Gd₂MoB₂O₉：Eu³⁺荧光粉的发光强度与商用红粉接近，同时色纯度优于商用红粉，因此它是一种具有发展潜力的新型红色荧光粉。本论文开展的商用红粉的改性研究对于探讨如何提高荧光粉对真空紫外光的吸收具有一定的指导作用，新型红色荧光粉的开发研究所取得的成果为进一步开发等离子显示器用红色荧光材料提供了实验参数。更多还原

【Abstract】 Eu³⁺ doped （Y, Gd）BO₃ has been widely used as a red phosphor for large-scale flat display panels because of its high conversion efficiency and thermodynamic stability. But （Y, Gd）BO₃:Eu³⁺ phosphor has been revealed several drawbacks such as poor color purity. Consequently, replacement solutions become necessary. Research in this way is focused on both the improvement of the existing phosphors and the development of new ones. The one aim of this work is to produce （Y, Gd）BO₃:Eu³⁺ phosphors by hydrothermal and sol-gel methods, and study their luminescence properties. The other aim is to find the new red phosphors based on the borate host and study the energy transfer process.Among the various possibilities to improve phosphors, the synthesis pathway is probably the most important. In this work, two wet chemistry methods, hydrothermal and sol-gel, are used to synthesize the （Y, Gd）BO₃:Eu³⁺ phosphors. The results show that （Y, Gd）BO₃:Eu³⁺ prepared by sol-gel process has the submicrosized and spherical shape, and its luminescent efficiency is higher than that prepared by solid state reaction, but the main emission is still orange emission. The （Y, Gd）BO₃:Eu³⁺ phosphors synthesized by hydrothermal process have different morphologies, such as rose-like, plate, spherical and fiber bundles. Compared with the commercial products, the spherical sample shows improved luminescence intensity and superior color chromaticity. With Eu³⁺ concentration increasing, the main emission peak changes from orange to red emission.As new red phosphors, Ca4GdO（BO₃）₃.Eu³⁺ and Sr₃Y₂（BO₃）₄:Eu³⁺ have the pure red emission, which is good for display application, but their luminescence efficiency is not satisfying. Their luminescence can be improved after La³⁺ and Al³⁺ co-doped. The host absorption is very important for the luminescence of phosphors. BaZr（BO₃）₂:Eu³⁺ shows good host absorption in VUV region, including the BO₃ host absorption, Ba-0 absorption band and Zr-O absorption band. Its luminescence intensity is strong but the emission is still orange, which restricts its application. Si⁴⁺ and Al³⁺ can sensitized the luminescence in the host of BaZr（BO₃）₂:Eu, but the Ti⁴⁺ and Gd³⁺ has no improvement effect, which is relation to the traps occurred in the host. After studying the luminescence of Ba_1-xEu_xB₈O₁₃ （0=x=0.2） phosphors, we find that the two luminescence centers in BaB₈O₁₃: Eu³⁺ show not only the competition emission but also the energy transfer from Eu²⁺ to Eu³⁺. As a novel phosphor, Gd₂MoB₂O₉:Eu³⁺ is synthesized by solid state reaction and its luminescence is first investigated. Under 147nm excitation, Gd_1.9Eu_0.MoB₂O₉ shows intense red emission at 626nm and its luminescence intensity is 85% than that of commercial red phosphor. The luminescent intensity of Gd₂MoB₂O₉:Eu³⁺ can be improved by doping M (M=Al³⁺, La³⁺, Y³⁺) and the Y³⁺ shows best sensitization effect.更多还原