Ca_2Y_8(SiO_4)_6O_2∶RE(RE=Eu,Tb)发光薄膜的制备及发光性能的研究

采用溶胶 凝胶法制备了稀土离子掺杂 (Eu3+ ,Tb3+ )的氧磷灰石三元稀土硅酸盐Ca2 Y8(SiO4 ) 6 O2 发光薄膜。通过X射线衍射 (XRD) ,红外光谱 (IR) ,扫描电镜 (SEM)等方法对薄膜的组成、结构、颗粒尺寸、形貌及厚度进行了研究 ,通过发光光谱对薄膜的发光性质进行了分析。XRD结果表明 70 0℃时薄膜尚处于非晶态 ,80 0℃时已开始有Ca2 Y8(SiO4 ) 6 O2 的物相形成 ,10 0 0℃时结晶已完全。这一点和红外光谱的结果相符。发光光谱测试表明Ca2 Y8(SiO4 ) 6 O2 ∶Eu3+ 薄膜显示了很强的红光发射 ,并以Eu3+ 的5D0 -7F2 (616nm)超灵敏跃迁为最强一组。Ca2 Y8(SiO4 ) 6 O2 ∶Tb3+ 的发射光谱由蓝光发射和绿光发射两部分组成 ,前者对应于5D3-7FJ,后者对应于5D4 -7FJ(J =6,5 ,4,3 ) ,且以5D4 -7F5(5 44nm)绿光发射为最强。

Luminescence of RE2+ (RE = Sm, Yb) in barium octoborate

The reduction process from trivalent to divalent state for Sm3+ and Yb3+ ions in barium berates (BaB8O13) prepared in air was observed. The luminescence properties of these divalent rare-earth ions were studied. Yb2+ shows an f-d broad emission band, due to the 4f(14) --> 4f(13)5d transition, while the Sm2+ ion shows an f --> f transition. From the spectra of Yb2+, and using the D-5(0) --> F-7(0) transition of Sm2+ as a structural probe, two crystallographic sites were found to be available for the cations in the host. Vibronic transitions of Sm2+ were observed at low temperature. BaB8O13 was found to be a good host for reducing the trivalent rare-earth ions to divalent state and to exhibit interesting spectroscopic properties,

The reduction of RE3+ in SrB6O10 prepared in air and the luminescence of SrB6O10 : RE2+ (RE=Eu, Sm, Tm)

The reduction of RE3+ to RE2+ (RE=Eu, Sm and Tm) in SrB6O10 prepared in air by high-temperature solid state reaction was observed. The luminescent properties of Eu2+ and Tm2+ show f-d transition and Sm2+ shows f-f transition at room temperature. Three crystallographic sites for Sm2+ in matrix are available. Vibronic transition of D-5(0)-F-7(0) of Sm2+ was studied. The coupled phonon energy about 108 cm(-1), was determined: from the vibronic transition. Due to the thermal population from D-5(0) level, (D1-FJ)-D-5-F-7 (J=0, 1, 2) transitions of Sm2+ were observed at room temperature. A charge compensation mechanism is proposed as a possible explanation.

Structural analysis of nonlinearities of Ca4ReO(BO3)(3) (Re = La, Nd, Sm, Gd, Er, Y)

From the chemical bond viewpoint, second-order nonlinear optical (NLO) tensor coefficients of the family of new oxoborates Ca4ReO(BO3)(3) (CReOB, Re = La, Nd, Sm, Gd, Er, and Y) have been theoretically predicted. The d(11) tensor coefficient of CReOB is predicted to be -11 d(36)(KDP), which is the largest d(ij) tensor that has been found in borate crystals. From the structural characteristic of CReOB, we find the isolated BO33- clusters play a dominant role in contributions to the total nonlinearity, and the largest d(11) tensor of CReOB-type crystals is also ascribed to these BO33- clusters. We also find the NLO property of this family does not change dramatically for different rare-earth elements. The details of the calculation of CGdOB only are presented.

MAl_2O_4:Eu~(2+)、RE~(3+)长余辉发光性质的研究

研究鳞石英结构碱土铝酸盐MAl2O4 Eu2+、RE3+(M=Mg,Ca,Sr,Ba;RE=Y,La,Ce,Pr,Nd,Sm,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu)的荧光及长余辉发光性质.其发光由Eu2+的4f-5d跃迁产生.Re3+作为辅助激活离子,提供合适的陷阱能级.即使用RE3+的特征波长激发,在MAl2O4 Eu2+、RE3+的发光中也观察不到RE3+的发光.基于其荧光,热释光,X-射线,红外光谱等实验结果,分析这一结构对稀土发光的影响,并总结其发光规律

Calculation of nonlinear optical coefficients of orthorhombic Re-2(MoO4)(3) crystals

From the chemical bond viewpoint, the second-order nonlinear optical (NLO) tensor coefficients of some Re-2(MoO4)(3) (ReMO)-type tare earth molybdates, with Re = Pr, Nd, Sm, Eu, Gd, Tb and Dy, have been calculated by using the chemical bond theory of complex crystals and the modified bond charge model. All kinds of constituent chemical bonds are considered in the calculation. The major part of the NLO properties of these ReMO crystals is found from the ReO7 groups. The NLO coefficients of these ReMO crystals decrease with Re from Pr to Dy. (C) 1998 Elsevier Science Ltd. All rights reserved.

Separation of Ce(IV) and RE(III) with hollow fiber membrane-based extraction

Separation of Ce(IV) and RE(III) was investigated by hollow fiber membrane-based extraction with contercurrent recirculating operation. The mass transfer coefficients of Ce(IV) and RE(III) and the effective factors to them were tested. The results show the mass transfer coefficient of Ce(IV) is larger than that of RE(III), and their mass transfer mechanism is different. The mass transfer of Ce(IV) was controlled by the resistance in water critical layer due to its more rapid interfacial reaction rate and larger distribution coefficient, which was different from RE(III) mass transfer with a slow interfacial reaction rate and small distribution coefficient. Ce(IV) was separated from the mixed solution of Ce(IV) and RE(III) by means of the difference of their mass transfer rates.

铈(Ⅳ)与RE(Ⅲ)的中空纤维膜基萃取分离

将中空纤维膜用于膜基萃取分离是７０年代开发的新分离技术，对金属离子的萃取分离［１～４］、有机有害物质的提取［５～７］及生物发酵产品和生物活性物质的提纯［８］均有报道．由于固体膜的相分离作用，中空纤维膜基萃取可实现非分散性分离操作，避免了液相萃取中液泛…

BaLaB_9O_(16):Re(Re=Eu,Tb)的真空紫外光谱特性的研究

近几十年来,人们对稀土离子的发光已进行了大量的研究,这些研究主要集中在紫外可见波段,对真空紫外区的光谱与能级研究的较少,相关光谱与能级缺乏足够的认识。近年来,随着大屏幕PDP的发展,寻找新型高效真空紫外激发的荧光体(等离子荧光体)已成为目前发光领域的研究热

Luminescence properties of sol-gel derived silica gels doped and undoped with RE-complexes (RE=Eu, Tb)

The luminescence properties of silica gels and silica gels doped with two rare earth complexes, Eu(TTA)(3) and Tb(o-CBA)(3) (TTA=thenoyltriffuocetate, o-CBA=o-chlorobenzoic acid) are reported and discussed. Pure silica gels show a blue luminescence, and the maximum excitation and emission wavelengths depend strongly on the solvents used. Both of the studied rare earth complexes exhibit the characteristic emissions of the rare earth ions in silica gels, i.e., Eu3+5D0-->F-7(J)(J=0,1,2,3,4), Tb3+5D4-->F-7(J)(J=3,4,5,6) transitions. Compared with the pure RE-complexes powder, the silica gels doped with RE-complexes show fewer emission lines of the rare earth ions. Furthermore the rare earth ion (Tb3+) presents a longer lifetime (1346 mu s) in silica gel doped with Tb(o-CBA)3 than in pure Tb((o-CBA)(3) powder (744 mu s). The reasons responsible for these results are discussed in the context.

Luminescence of RE3+ and energy transfer from Gd3+ to RE3+ (RE=Dy, Eu) in SrGdAlO4:RE3+

Spectral properties of Gd3+, Dy3+ and Eu3+ ions in SrGdAlO4 are reported in detail A cooperative vibronic transition of Gd3+ and the emission from the higher D-5(J) (J=1, 2, 3) levels of Eu3+ were observed. Energy transfer occurs from Gd3+ to Dy3+ and to Eu3+. The influence of Gd3+ and Dy3+ concentrations on the luminescence intensity is discussed.

CaAl_3BO_7:RE(RE=Ce,Gd,Tb)中稀土离子的光谱特性

采用固相反应法合成了ＣａＡｌ３ＢＯ７ＲＥ（ＲＥ＝Ｃｅ，Ｇｄ，Ｔｂ），研究了Ｃｅ３＋，Ｇｄ３＋和Ｔｂ３＋的光谱特性．发现铈离子周围存在较强的晶场，使基态的４ｆ能级劈裂较大，从而导致铈离子的特征发射峰重叠较大；Ｃｅ３＋的５ｄ能级明显低于Ｇｄ３＋的６Ｉ、６Ｐ能级；Ｃｅ３＋和Ｔｂ３＋之间存在有效的能量传递

Sol-gel synthesis and luminescence of Y4Al2O9:RE3+(RE=Eu, Tb)

Y4Al2O9 (YAM) was prepared by a sol-gel process, using yttrium and aluminum citrate complexes as precursors. The sol-gel process produced single-phase YAM at 900 degrees C, as opposed to the conventional solid-state reaction, which led to the formation of other phases, even if at 1600 degrees C. The emission and excitation spectra of Eu3+ and Tb3+ in YAM showed the existence of two luminescence centers, agreeing with the crystal structure of YAM. The spectral properties of the samples are discussed.

A STUDY ON THE LUMINESCENCE PROPERTIES OF EU3+ AND DY3+ IN M(2)RE(8)(SIO4)(6)O-2 (M=MG, CA RE=Y, GD, LA)

In this paper, the luminescence properties of Eu3+ and Dy3+ in the oxyapatites M(2)RE(8)(SiO4)(6)O-2 (M=Mg, Ca; RE=Y, Gd, La) were studied. The spectral characters of Eu3+ were discussed in relation to the crystal structure. The dependence of the red-to-orange intensity ratio and the position of the charge transfer band of Eu3+ and the yellow-to-blue intensity ratio of Dy3+ together with their fluorescence intensities (I-R for Eu3+ and I-Y for Dy3+) On the M(2+) and the substitution of BO45- and PO43- for SiO44- was discussed. Finally, the concentration quenching of Dy3+ luminescence was reported.