Tb^(3+)和Dy^(3+)共激活的LaOBr阴极射线发光特性

固体发光材料中,稀土离子间的光学性质和能量传递已作了大量工作。但是,在阴极射线(CR)激发下,稀土离子间相互作用和发光性质的变化,特别是有关能量传递还很少报道。LaOBr:Tb^(3+)和LaOBr:Tm^(3+)是一类高效的阴极射线发光和X射线增感屏用荧光粉,人们曾对LaOBr:Ce^(3+),Tb^(3+)的发光性质进行了研究。

LaOBr中Ce—Tb、Tm—Er间能量传递的光声光谱和光致发光研究

本文首次报导了发光材料中两个不同稀土离子间能量传递的光声光谱研究。测量了LaOBr:Tb,Ce和LaOBr:Er,Tm体系的光声光谱,结合它们的光致发光特性,讨论了Ce^(3+)对Tb^(3+)的敏化、Tm^(3+)对Er^(3+)的猝灭。基质中掺入两种不同稀土离子后光声光谱的变化进一步证实了它们间的能量传递都伴随着多声子过程。分析LaOBr:Er,Tm的光声光谱,对Er^(3+)r的红光猝灭的机制提出了新的解释。

LaOBr:Eu^(3+)的制备及发光特性

采用固相合成法制备了Eu3+掺杂的LaOBr发光材料,研究了不同物质的量分数的Eu3+对发光性质的影响,其中Eu3+的物质的量分数为0.1%,0.2%,0.5%,1%.X线衍射图表明:所得样品为纯相的LaOBr.测量了不同物质的量分数的激发谱、发射谱及荧光寿命.通过对Eu3+衰减曲线的拟合,得到在相同Eu3+的物质的量分数下,从电荷迁移带跃迁到5 D0能级时间比5 D2能级跃迁到5 D0能级时间短,但从5 D0能级跃迁到基态能级的时间基本相同,说明Eu3+之间存在交叉弛豫现象.利用Judd-Oflet理论,从发射光谱获得了Eu3+的光学跃迁强度参数Ωλ(λ=2,4).

Energy Transfer in LaOBr:Tb,Gd

Energy transfer in LaOBr:Tb_(0.0075),Gd_x(x<0.30)was investigated via excitation spectra,emission spectra,fluorescence decay function and X-ray diffraction.Effective energy transfer from Gd to Tb was found. With excitation of λ=275nm,no Gd^(3+)but only Tb^(3+)emission has been observed,and the integrated intensity of Tb^(3+)emission increases with increasing Gd content up to～5.5 times(in the sample of x=0.30)compared to that of the sample without Gd.The existense of Gd in the sample slows down the Tb^(3+)flourescence decay,and most likely the electric dipole-dipole interaction dominates the energy transfer process.

Luminescence Characteristics and Energy Transfer Machanismof LaOBr:Tb^(3+) (Dy^(3+))

The rare earth luminescence materials LaOBrfTb3+(Dy3+) were synthesized at high temperature,and the structure and luminescence characteristics were studied. The co-doping Dy3+ may make the energy of 5D3 of Tb3+ transfer to 5D4 level, which makes the emission of 5D4-7FJ (J=0,1... 6), specially of 5D4-7F5, enhance obviously, and the total brightness is increased by about 40% in comparison with the samples without Dy3+ cations, as a result of the energy transfer of dipole-dipole interaction.

溴氧化镧的缺陷发光

用高温固相法合成了具有缺陷发光的溴氧化镧基质。对样品进行了X-射线衍射、荧光光谱和热释光谱的测试。荧光光谱分析得出在1000℃合成溴氧化镧基质在350nm到500nm存在两个宽带发射,通过与LaOF、LaOCl的荧光光谱和热释光谱对比,得出溴氧化镧基质的发光归结于溴的缺陷,通过计算发现两种不同类型的缺陷能级分别为0.74eV,0.70eV。