【作者】 李峰；

【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】 六铝酸盐基发光材料由于其在等离子显示器（plasma display panels，PDPs）与无汞荧光灯等显示照明器件上的应用而引起了普遍关注，其中BaMgAl₁₂O₁₉：Mn²⁺与BaMgAl₁₀O₁₇：Eu²⁺（BAM）已作为商用材料而得到了广泛应用。然而这两种发光材料的性能仍未能满足PDP与无汞荧光灯的需要，主要表现为：BaMgAl₁₂O₁₉：Mn²⁺的发光效率与余辉时间有待改进，而BaMgAl₁₀O₁₇：Eu²⁺的稳定性较差。针对PDP与无汞荧光灯等显示照明器件的发展需要，本论文对两种商用真空紫外发光材料BaMgAl₁₂O₁₉：Mn²⁺与BaMgAl₁₀O₁₇：Eu²⁺展开了一系列的研究；同时还初步考察了Dy³⁺激活的BaMgAl₁₁O₁₉的真空紫外—紫外发光性能，探讨Dy³⁺激活发光材料在无汞荧光灯、LED等照明器件上的潜在应用。通过上述研究得到的一系列研究成果对于了解六铝酸盐基发光材料的发光机理、推动其在PDP与无汞灯上的应用具有重要的理论意义及应用价值。第一，在真空紫外激发下，基质BaMgAl₁₂O₁₉可有效地将能量传递给发光中心Mn²⁺。本论文通过研究Ba_0.75Al₁₁O_17.25-x BaMgAl₁₀O₁₇：0.1 Eu²⁺的真空紫外激发光谱，对尖晶石层中AlO₄^5-、AlO₆^9-与MgO₄^6-等各基团的光谱吸收位置进行了归属，这为研究六铝酸盐基发光材料在真空紫外激发下的发光机理、改善BaMgAl₁₂O₁₉：Mn²⁺与其他商用六铝酸盐基发光材料的真空紫外发光性能打下了基础。第二，对于PDP等显示器件而言，BaMgAl₁₂O₁₉：Mn²⁺的余辉时间仍然偏长，这是由于Mn²⁺的⁴T₁→⁶A₁跃迁发射是宇称与自旋双重禁戒的跃迁。本论文通过研究Mn²⁺掺杂浓度对Ba_0.75Al_11-xO_17.25：x Mn²⁺的色度、发光强度、余辉时间等发光特性的影响后，发现适当增加Mn²⁺的掺杂浓度可以在保证良好的色纯度和亮度的基础上减小余辉时间；通过使用EPR、穆斯堡尔谱等测试手段，首次证明了在BaMgAl₁₂O₁₉：Mn²⁺中存在Mn²⁺-Mn²⁺对中心，正是该中心含量的变化导致了余辉时间、发射峰位等发光特性的变化，并且该中心的形成方式是通过Mn²⁺占据Ba_0.75Al₁₁O_17.25中的Al（2）格位实现的。第三，本论文考察了ns²离子与Zn²⁺掺杂对BaMgAl₁₂O₁₉：Mn²⁺发光特性的影响。研究结果表明：ns²离子中的Bi³⁺与Sb³⁺，以及Zn²⁺均可有效的提高BaMgAl₁₂O₁₉：Mn²⁺的发光强度，其中以Sb³⁺的效果最佳；而这三种离子的掺杂对于余辉特性均无明显影响。第四，本论文采用反相微乳法与沉淀法相结合制备了Mn²⁺激活的六铝酸钡纳米发光材料，并研究了样品的真空紫外发光特性。研究结果表明：不同的反相微乳体系与溶液／油相比对样品的形貌有决定性影响，颗粒形貌主要有球状、棒状等；球状Ba_0.999Al_11.9O₁₉：0.1 Mn²⁺，0.001 Eu²⁺的发光强度、亮度、色度等性能均优于块体材料BaAl_11.9O₁₉：0.1 Mn²⁺；真空紫外激发下，球状纳米Ba_0.75Al_11-xO_17.25：xMn²⁺的猝灭浓度高于块体材料；颗粒形貌对样品发光性能有重要影响。第五，采用溶胶—凝胶法对BAM颗粒进行了MgF₂与CaF₂的包覆以提高其热稳定性。结果表明包覆后的BAM的抗热劣化能力均得到了明显的改善，其中以MgF₂包覆的效果最好。第六，对Dy³⁺激活的六铝酸盐材料LaMgAl₁₁O₁₉的发光特性以及Bi³⁺、Sb³⁺与Zn²⁺掺杂对Dy³⁺发光的影响进行了初步的探索。结果表明：在真空紫外—紫外区间内多个应用波长（147nm、254nm、365nm）的激励下，Dy³⁺在LaMgAl₁₁O₁₉中的发射的色坐标均位于CIE 1931色品图中的白光区；在上述三个应用波长的激发下，Bi³⁺与Zn²⁺均可敏化Dy³⁺的⁴F_9／2-⁶H_15／2与⁴F_9／2-⁶H_13／2跃迁发射，其中以Bi³⁺的敏化效果最为显著，并且随着共掺杂离子Bi³⁺或Zn²⁺含量的增加，样品的色坐标向黄光区移动，色温也随之增加。更多还原

【Abstract】 Phosphors based on hexaaluminates have attracted a great deal of attention because of their application in plasma display panels （PDPs） and Hg-free lamps, among which BaAl₁₂O₁₉:Mn²⁺ and BaMgAl₁₀O₁₇:Eu²⁺ （BAM） have been widely used as commercial phosphors. However, the former’s luminescence efficiency, decay time and the latter’s stability still need to be improved to fulfill the demands of the development of PDPs and Hg-free lamps. Accordingly, these two phosphors were studied systematically in this thesis. Furthermore, the luminescence properties of Dy³⁺ activated LaMgAl₁₁O₁₉ under vacuum ultraviolet （VUV） and UV excitation were also preliminarily investigated for the potential application in Hg-free lamps and LEDs of Dy³⁺ activated phosphors. The results derived from the above research would contribute greatly to the understanding of the luminescence mechanism of hexaaluminate phosphors and advance their application in PDPs and Hg-free lamps.1. The host of BaAl₁₂O₁₉ can efficiently transfer the energy to the luminescent center of Mn²⁺ under VUV excitation. By analyzing the VUV excitation spectra of Bao.75AlnO17.25-x BaMgAl₁₀O₁₇:0.1 Mn²⁺ solid solution, the optical absorption positions of the groups of AlO₄^5-, AlO₆^9- and MgO₄^6- in the spinel blocks were assigned, which would lay a solid foundation for the study of the luminescence mechanism of BaAl₁₂O₁₉:Mn²⁺ and other commercial hexaaluminate phosphors and the improvement of their VUV luminescence properties.2. Because of the doubly spin and parity-forbidden ⁴T₁→⁶A₁ transition of Mn²⁺, the decay time of BaAl₁₂O₁₉:Mn²⁺ is still somewhat too long for its application in PDPs. In this thesis, the influences of the concentration of Mn²⁺ on the luminescence properties of Ba_0.75Al_11-xO_17.25:x Mn²⁺ were studied. The results indicates that increasing the concentration of Mn²⁺ properly can decrease the decay time to some extent avoiding the deterioration of color purity and brightness. According to the results of EPR and Mossbauer Spectroscopy, it is considered that Mn²⁺ paired centers are formed by Mn²⁺ occupying Al（2） sites in Ba_0.75Al₁₁O_17.25 and thus induce the variation of luminescence characteristics.3. The influences of the co-doping of ns² ions and Zn²⁺ on the luminescence characteristics of BaAl₁₂O₁₉:Mn²⁺were evaluated in this thesis. The results indicates that the co-doping of Bi³⁺, Sb³⁺ and Zn²⁺ can effectively enhance the luminescence intensity of BaAl₁₂O₁₉:Mn²⁺, among which the co-doping of Sb³⁺ is the most effective. The co-doping of these three kinds of ions didn’t show obvious effects on the decay behavior of BaAl₁₂O₁₉:Mn²⁺.4. Mn²⁺ activated barium hexaaluminate nanophosphors with spherical and rod-like morphologies were successfully synthesized by a reverse microemulsion method combined with a precipitation process, and their luminescence properties under VUV excitation were investigated for the first time. The luminescence intensity, brightness and color purity of Ba_0.999Al_11.9O₁₉:0.1 Mn²⁺, 0.001 Eu²⁺ spherical nanophosphor are better than those of bulk BaAl_11.9O₁₉:0.1 Mn²⁺; the critical Mn²⁺ concentration ofBa_0.75Al_11-xO_17.25: Mn²⁺ spherical nanophosphor is higher than bulk counterpart; the particle morphology has great impact on the luminescence properties of Mn²⁺ activated barium hexaaluminate nanophosphors.5. BAM particles were successfully coated with MgF₂ and CaF₂-coatings by a sol-gel process. The results indicate that the thermal stability of coated BAM is obviously improved and the effect of MgF₂-coating is better than that of CaF₂.6. The luminescence properties of LaMgAl₁₁O₁₉:Dy³⁺ co-doped with Bi³⁺, Sb³⁺and Zn²⁺ in UV-VUV region were preliminarily studied for the first time. The results exhibit that Dy³⁺ activated LaMgAl₁₁O₁₉ shows white-light emission under a variety of wavelength excitation （147 nm, 254 nm and 365 nm）. The co-doping of Bi³⁺ and Zn²⁺ can both sensitize the emission of Dy³⁺ under the above three excitation sources with the movement of chromaticity coordination towards the yellow region, and the sensitizing effect of Bi³⁺ is better than that of Zn²⁺.更多还原