SrAl2O4：Eu^2＋,Dy^3＋荧光材料的发光性质

我们在本文中制作了五种不同ＳｒＡｌ２Ｏ４：Ｅｕ＾２＋和Ｄｙ＾３＋的样品。样品分别是ＳｒＡｌ２Ｏ４基质的α相和β相的粉末和片状样品,以及单晶样品。我们对所有样品进行了形貌的ＳＥＭ研究。我们还对α相和β相粉末样品及片状样品以及α相单晶样品的荧光发射谱进行了测量。它们的荧光发射的中心波长为５２０ｎｍ,对应于ＳｒＡｌ２Ｏ４基质中的Ｅｕ＾２＋的４ｆ＾６５ｄ＾１的＾２ｅｇ激发态到４ｆ＾７的＾８Ｓ７／２的跃迁发     

CaxSr1—xS：Bi,Tm,Cu和CaS：Eu荧光材料的研究

所作的一部分工作是对长余辉的荧光材料ＣａｘＳｒ１－ｘＳＢｉ，Ｔｍ，Ｃｕ（ｘ＝０，０．７５，１）进行了研究．ＣａＳ和ＳｒＳ两种基质材料高温互溶后，因为基质的晶体微结构上的变化引起Ｂｉ３＋离子荧光效应的变化，即发光的发射波数发生改变．另一部分工作是对ＣａＳＥｕ加入陷阱机制后发光效应的研究．新的陷阱机制的引进，使得其余辉效应有较大的延长．     

结构稳定的高质量荧光材料CaAl_4O_7:Tb~(3+),Ce~(3+)

在本文中制作了CaAl4 O7:Tb3+,Ce3+新荧光材料。烧结温度为 130 0℃ ,烧结环境为N2 + 5 %H2还原气。TEM实验结果表明样品的粒度小于 1μm。X 射线和HRTEM实验证实 ,样品的晶格点阵十分规则 ,而且没有发现掺杂和助溶剂对基质结构的影响 ,表现出十分好的材料质量。光学实验观测到对应于Tb3+离子的 5D4 到7FJ(J=6 ,5 ,4,3) 的跃迁发射峰在 485 ,5 45 ,5 90和 6 2 0nm。CaAl4 O7:Tb3+,Ce3 +降低了基质结构的不确定性 ,同时保持了Tb3+发光中心的特性。     

LUMINESCENCE OF Bi3+ and Eu2+ DOUBLE CENTERS DOPED IN CaS HOST

In this work, double-center.doped luminescent material CaS:Bi³⁺, Eu²⁺ was made via flux NH₄Cl by sintering in excess sulfur environment. The sample had a purplish red net luminescent color. Excitation spectra at both red, 650 nm and blue, 487 nrn were taken. The red emission from Eu²⁺ center was mainly come from the 4f⁶5d¹ absorption in the CaS host. The blue emission from the Bi³⁺ center on the other hand showed no big difference from the singly doped CaS:Bi³⁺ materials in excitation spectrum. Emission spectra were obtained at excitaton of 270nm and 300nm. Stokes shift was moved about 20-30nm, under different point excitation. Emission peaks of both Bi³⁺ and Eu²⁺ centers appeared at 463nm, 642.5nm by 270nm excitation and 487 nm, 620 nm by 300 nm excitation respectively. After-glow decay cures were also obtained and the shapes of decay curves are similar and it is due to the single hole-trap system by lattice defects.     

PHASE DEPENDENCE OF LUMINESCENT EMISSION OF Eu2+ DOPED SrAl2O4

In this work, we made five samples of SrAl₂O₄: Eu²⁺, Dy³⁺, the α phase and β phase SrAl₂O₄:Eu²⁺,Dy³⁺ powder and pellet samples, and α phase single crystal. We have measured the emission spectra of all the samples. All the emission peaks are around 520 nm, which correspond to the transition from 4f⁶5d¹(²E_g) to 4f⁷(⁸S_7/2) of Eu²⁺ in SrAl₂O₄ host. The intensity of emission of the β phase is stronger than that of the α phase. We believe that it is because the Eu²⁺ ions have occupied the two types of sites in the α phase SrAl₂O₄ host and the lifetime of the transition of Eu²⁺ in the A site is longer than that in the B site. This result also proves that the β phase of the material is brighter than the α phase. In addition, the β phase can be achieved by quenching technique.     

严懋勋实验室与长余辉荧光材料

美国乔治亚大学(University of Georgia,UGA)物理系严懋勋(W. M. Yen)教授在他的后期工作中,主要从事长余辉荧光材料的基础研究和实际应用研究.在这些工作中,他起着组织、领导和支持的作用.因为他的倡导,长余辉荧光材料的研究在美国佐治亚大学取得很多成果.尤其是在长余辉的基础研究中,对长余辉基理的阐述,为长余辉材料的开发奠定了指导思想.作者在本文中将以记述的方式仅对其中一些主要成果加以介绍,并以此文表达对严懋勋教授的怀念.     

一类最优组合批处理码

Ishai等人首先提出了批处理码的概念,Peterson等人从纯组合的观点定义了(n,N,k,m)-组合批处理码:即是一个n元集和它的m个子集组成的集合系统,对于整数尼,满足任意k个元素都能从每个子集中至多读取1个元素(可以一般化为t个元素)来取得,此时m个子集中元素的总数为N.对给定的参数n,k,m,确定N的最小值N(n,k,m)是该问题研究的中心内容,它不仅具有理论意义,而且有着重要的使用价值.到目前为止,除了一些极特殊的参数以外,当k≥5,m+3≤n(m k-2)时,N(n,k,m)的值还没有被确定.本文给出了N(m+3,5,m)=m+11(m≥7),N(9,5,6)=18,N(m+3,6,m)=m+13(m≥8),N(10,6,7)=21.得到的结果部分解决了:Peterson等人提出的未解决问题.     

结构稳定的高质量荧光材料CaAl4O7：Tb^3＋,Ce^3＋

在本文中制作了CaAl4O7:Tb^3 ,Ce^3 新荧光材料。烧结温度为1300℃,烧结环境为N2＋5％H2还原气。TEM实验结果表明样品的粒度小于1μm。X－射线和HRTEM实验证实,样品的晶格点阵十分规则,而且没有发现掺杂和助溶剂对基质结构的影响,表现出十分好的材料质量。光学实验观测到对应于Tb^3 离子的^5D4到^7FJ(J=6,5,4,3)的跃迁发射峰在485,545,590和630nm。CaAl4O7:Tb^3 ,Ce^3 降低了基质结构的不确定性,同时保持了Tb^3 发光中心的特性。     

LUMINESCENCE OF Bi3+ and Eu2+ DOUBLE CENTERS DOPED IN CaS HOST

In this work, double-center.doped luminescent material CaS:Bi³⁺, Eu²⁺ was made via flux NH₄Cl by sintering in excess sulfur environment. The sample had a purplish red net luminescent color. Excitation spectra at both red, 650 nm and blue, 487 nrn were taken. The red emission from Eu²⁺ center was mainly come from the 4f⁶5d¹ absorption in the CaS host. The blue emission from the Bi³⁺ center on the other hand showed no big difference from the singly doped CaS:Bi³⁺ materials in excitation spectrum. Emission spectra were obtained at excitaton of 270nm and 300nm. Stokes shift was moved about 20-30nm, under different point excitation. Emission peaks of both Bi³⁺ and Eu²⁺ centers appeared at 463nm, 642.5nm by 270nm excitation and 487 nm, 620 nm by 300 nm excitation respectively. After-glow decay cures were also obtained and the shapes of decay curves are similar and it is due to the single hole-trap system by lattice defects.     

Ca0.9Sr0.1S:Bi3+,Tm3+荧光材料的光学性质

Ｃａ０．９Ｓｒ０．１Ｓ：Ｂｉ＾３＋,Ｔｍ＾３＋是一种复合掺杂复合基质荧光材料。在此给出了４４０ｎｍ和５２０ｎｍ发射的激发谱,２５０ｎｍ到３５０ｎｍ的激发的发射谱,以及４００ｎｍ到５２０ｎｍ的荧光衰减谱。紫外光区域的激发谱表明,Ｃａ０．９Ｓｒ０．１Ｓ：Ｂｉ＾３＋,Ｔｍ＾３＋有两个主要的能量传递体系,３２５ｎｍ的复合掺杂中心Ｔｍ＾３＋的ＣＴ跃迁激发体系,和Ｂｉ＾３＋的自身激发体系。紫外激发的荧光发射谱