【作者】 王大伟；

【导师】 黄世华；

【作者基本信息】 北京交通大学 ， 光学， 2008， 博士

【摘要】 稀土掺杂的真空紫外荧光材料有望应用在无汞荧光灯，高效等离子体显示器件，和快速闪烁体方面，近年来随着同步辐射设备等真空紫外实验手段的不断完善和对真空紫外荧光材料应用价值的不断认识，大量的真空紫外荧光材料被广泛研究，其目的是为了开发更加实用的真空紫外荧光材料，同时扩展对于稀土离子高能态性质的认识，因此对于真空紫外荧光材料的研究不仅是实际应用的需要，同时也是稀土离子能级理论发展的必然。本文研究的内容主要分为以下几部分：1．验证了原始的和修正的Judd-Ofelt理论在SrAl₁₂O₁₉和LaF₃中Pr³⁺¹S₀能级的适用性，结果表明：应用修正的Judd-Ofelt理论可以获得更加接近实验值的计算值，因此在Pr³⁺¹S₀能级适用Judd-Ofelt理论时，对其进行修正是必要的。2．研究了Pr³⁺掺杂的SrAl₁₂O₁₉和Y₃Al₅O₁₂中缺陷对Pr³⁺发光的影响和SrB₄O₇和LaB₃O₆体系中Pr³⁺¹S₀的热激发过程。结果表明：在20K下基质的缺陷发射会较强，在100K以上¹S₀态的热激发过程会增强，二者都会降低Pr³⁺¹S₀发射的量子效率，因此在高效量子剪裁材料中，应该避免这两个过程的出现。3．研究了LiLuF₄：Pr³⁺或Nd³⁺的真空紫外发光性质，从激发光谱和衰减曲线都可以判断Lu³⁺到Pr³⁺或Nd³⁺有能量传递过程。在大于基质带隙能量的65nm或90nm激发下，Pr³⁺或Nd³⁺4f^n-15d发射的衰减曲线是双指数线型，这是由Pr³⁺或Nd³⁺到缺陷的能量传递过程所导致的。LiLuF₄：Pr³⁺或Nd³⁺4f^n-15d发射的衰减时间小于17．5ns，因此从响应时间方面来说，LiLuF₄：Pr³⁺或Nd³⁺是很有前景的闪烁体材料。4．研究了粉末和单晶YPO₄:Nd³⁺在不同温度，不同激发波长或发射波长和不同浓度下的光谱和衰减性质，结果表明在大于带隙宽度激发下，单晶样品表现出更强的缺陷发光性质，在低于带隙宽度激发下，粉末样品有更强的缺陷发光特性，二者均在200K时，Nd³⁺4f^n-15d发射衰减曲线具有较慢的上升沿时间，但其衰减时间均小于9ns，因此从响应时间角度分析，YPO₄：Nd³⁺也是较好的闪烁体材料。更多还原

【Abstract】 The vacuum-ultraviolet （VUV） phosphors doped with rare earths was a kind of promising materials which could be used in mercury-free fluorescent lamps, high-efficient plasma display panels, and fast scintillator. With the development of VUV experimental methods including synchrotron station and the requirements for high-efficient VUV phosphors, a lot of VUV phosphors were studied to get more applicable VUV phosphors and to expand the understand for the high-energy levels of Lanthanides. So the research about the VUV phosphors was not only the need for application, but also the tendency of the development of the lanthanide energy levels theory.This thesis could be divided into several parts:1. Firstly, the thesis verified the application of original and modified Judd-Ofelt theory to ¹S₀ state of Pr³⁺. The results showed that it was possible to get more feasible calculating results using modified Judd-Ofelt theory. Therefore, it was necessary to modify the original Judd-Ofelt theory which would be applied to Pr^{3+ 1}S₀.2. Secondly, influence of defect on the luminescence of Pr³⁺ in aluminates and the thermal excitation from ¹S₀ state of Pr³⁺ in borates were also studied. As the results identified, at 20K the defect emission in host would be increased and above 100K the thermal excitation of ¹S₀ could be strengthened, and it was also concluded that both defects in hosts and thermal excitation from high-energy levels could decrease the quantum efficiency of Pr^{3+ 1}S₀, so these processes should be avoided for high-efficient quantum cutting materials.3. Thirdly, the VUV luminescent and decay properties of Pr³⁺ or Nd³⁺ doped in LiLuF₄ were also reported. From excitation spectra and decay curves, it could be concluded that there were energy transfer processes from Lu³⁺ to Pr³⁺ or Nd³⁺. Under excitation （65nm or 90nm） above the bandgap the decay curves of Pr³⁺ or Nd³⁺ were second-order exponential figures which were induced by the energy transfer processes from activators to defects. The lifetimes were less than 17.5ns. So from the response times the Pr³⁺ or Nd³⁺ activated LiLuF₄ was a kind of promising scintillator materials.4. The spectral and decay properties of powder and single crystal YPO₄:Nd³⁺ at different temperatures, different excitation or emission wavelength, and concentrations were also studied. The results showed that under excitation over the bandgap single crystal sample exhibited stronger defect luminescence, on the contrast the powder sample would show stronger defect emission under the excitation below the bandgap. At 200K, both powder and single crystal samples had the slower build-up times for Nd³⁺ 4f^n-15d emission, and the lifetimes were less than 9ns. Accordingly, from the aspect of response times YPO₄:Nd³⁺ was also a kind of better scintillator materials.更多还原