Luminescence properties of K1/2Bi1/2TiO3:Pr3+ and Na1/2Bi1/2TiO3:Pr3+

The luminescence properties of K(1/2)Bi(1/2)TiO(3):Pr(3+) and Na(1/2)Bi(1/2)TiO(3):Pr(3+) powders are investigated in the temperature range 10-600 K. The experimental data are interpreted on the basis of metal-to-metal charge transfer processes and by considering Bi(3+)-to-Pr(3+) sensitization effects.     

Superbroadband near-IR emission from praseodymium-doped bismuth gallate glasses

Superbroadband near-infrared (NIR) emission covering 1250 to 1680 nm wavelength has been obtained in praseodymium (Pr(3+)) singly doped bismuth gallate glasses. The emission originates from the (1)G(4)→(3)H(5) and (1)D(2)→(1)G(4) transitions at 1330 and 1490 nm wavelengths, respectively, and is due to the extremely low phonon energy (～690 cm(-1)) and the unique ligand field of the glasses. It is shown that the emission line shape can be modified by adjusting the Pr(3+) concentration and the energy transfers involved. The results confirm that other than bismuth (Bi), chromium (Cr), nickel (Ni), and other chemical elements, Pr(3+) singly doped system is a promising alternative in achieving superbroadband NIR emission.     

Enhanced emission of 2.7 μm pumped by laser diode from Er3+/Pr(3+)-codoped germanate glasses

A novel Er(3+)/Pr(3+) codoped germanate glass was fabricated and analyzed. Efficient emission at 2.7 μm from the glass was observed upon excitation of a conventional 980 nm laser diode. The 2.7 μm emission characteristics and energy transfer (ET) were investigated. Population inversions between ?I(13/2) and ?I(11/2) levels have been achieved, and an enhanced emission from 2550 to 2800 nm was obtained. Large ET efficiency of 95% indicates that the ET process from Er(3+) to Pr(3+) (?I(13/2), 3H?)→(?I(15/2), 3F?) is efficient and that Pr(3+) can enhance the emission of 2.7 μm by quenching the lower laser level of Er(3+) via ET.     

Optical Properties of Yb~(3 ) Doped Bi_2O_3-3B_2O_3 Glass

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Synthesis,Crystal Structure,and Thermal Properties of Substituted Titanates Bi2Pr2Ti3O12 and Bi2Nd2Ti3O12

Physics of the Solid State - Titanates Bi2Pr2Ti3O12 and Bi2Nd2Ti3O12 have been obtained by the solid-phase synthesis using sequential annealing of the Bi2O3, Nd2O3, Pr6O11, and TiO2 stoichiometric...     

Pressure-induced phase transition in LiLuF4:Pr3+ investigated by an optical technique

The luminescence and luminescence kinetics of LiLuF(4) doped with 1.5 at.% of Pr(3+) obtained at high hydrostatic pressure changing from ambient to 220 kbar applied in a diamond anvil cell are presented. It has been shown that pressure causes shift of the emission lines toward the red with rates of the order of single cm(-1) kbar(-1). The pressure-induced phase transition from tetragonal to fergusonite structure for pressure above 100 kbar was observed. The crystal field calculations performed showed that this phase transition reduces the point symmetry of the Pr(3+) site from the S(4) to the C(2) point group.     

HO3+单掺杂及其与Yb3+、Er3+共掺杂硼硅酸盐玻璃上转换发光的光谱分析

采用高温固相烧结法制备了HO3+单掺杂、HO3+/Yb3+共掺杂、HO3+/Er3+共掺杂和Ho3+/Yb3+/Er3+共掺杂等系列硼硅酸盐玻璃,测量了样品的激发光谱和发射光谱.结果表明:Ho3+单掺杂样品的激发光谱与发射光谱的强度随其浓度增加而逐渐减弱,原因是高浓度掺杂导致Ho3+离子产生猝灭效应;Ho3+/Yb3+...     

温度对于掺杂在SrAl12O19中Pr3+4f5d发射的影响

测量了在真空紫外光激发下,SrAl12O19∶Pr3 在不同温度(308~483 K)时的发射光谱,同时观测到了电偶极禁戒的4f2→4f2和电偶极允许的4f5d→4f2跃迁。随温度升高,4f5d→4f2与1S0发射的相对强度逐渐增强。运用Pr3 4f2组态最高的能级—1S0能级和4f5d组态最低能级间的热平衡模型成功解释了SrAl12O19∶Pr3 发射光谱随温度变化的现象。     

太阳电池用YVO_4∶Eu~(3+)下转换材料的掺杂改性研究

为进一步提高YVO_4材料的下转换发光性能,在改进后的溶胶-凝胶法制备的YVO_4∶Eu~(3+)中,通过掺入Bi~(3+)来拓宽其在紫外波段的光谱吸收并提高其发光强度,通过掺入P~(5+)达到以PO_4~(3-)部分取代VO_4~(3-)来改善YVO_4∶Eu~(3+)的光输出稳定性及温度猝灭特性的目的。研究表明,掺入的Bi~(3+)和P~(5+)可成功取代YVO_4晶格中的Y~(3+)和V~(5+)。当Bi~(3+)掺入量较少时,样品仍然为四方晶系,Bi~(3+)较好地取代了Y~(3+)的晶格位置,形成单相的晶体结构。而在掺入少量的P~(5+)之后,YVO_4与YPO_4之间形成了均匀的固溶体。在350 nm激发光源作用下,当Bi~(3+)和P5+掺杂摩尔分数分别为0.04和0.10时,发光强度达到最大,特别是YV0.90P0.10O4∶0.05Eu~(3+)在619 nm处的发光强度要比YVO_4∶0.05Eu~(3+)的发光强度增大1.9倍。     

Optical Properties of Yb3+ Doped Bi2O3-3B2O3 Glass

The transmission and fluorescence spectra of Yb3+ doped Bi2O3-3B2O3 glass were measured. The emission cross section have been evaluated using the measured absorption apectra and principle of reciprocity. The measured long lifetime τm(1.0 ms) and large emission cross section σem(1.423 pm2) indicate that Yb3+ doped Bi2O3-3B2O3 glass is a promisiong laser material.     

Y3Al5O12:Ce3+,Cr3+和Y3Al5O12:Ce3+,pr3+,Cr3+荧光粉体系中的能量传递

通过在YAG:Ce3+和YAG:Ce3+,pr3+荧光粉体系中分别掺入Cr3+离子来提高蓝光管芯白光LED的显色指数.Cr3+离子的加入,增加了红光发射,这归因于Cr3+的2E-4 A2跃迁的零声子线和声子边带发光.Ce3+→Cr3+的能量传递是增强红光发射的重要方式,在YAG:Ce3+,Cr3+体系中,由发射光谱得到...     

Evidence for visible quantum cutting via energy transfer in SrAl12O19:Pr,Cr

Evidence for visible quantum cutting involving the emission of two visible photons for each vacuum-ultraviolet (VUV) photon absorbed is demonstrated in SrAl(12)O(19):Pr,Cr using synchrotron radiation as one of the excitation sources. Upon VUV excitation of the 4f5d states of Pr(3+), quantum cutting could occur by a two-step energy transfer from Pr(3+) to Cr(3+) by cross relaxation and sequential transfer of the remaining excitation energy. A theoretical visible quantum efficiency of 147% is estimated in SrAl(12)O(19):2% Pr,5% Cr, suggesting the possibility of a VUV phosphor with visible quantum efficiency higher than 100% based on Pr(3+)-Cr(3+) pair in oxide materials.     

Spectral investigation of R,Ce:YAG(R: Pr~(3+), Eu~(3+), Gd~(3+)) single crystals and their applications in white LEDs

Eu3+, Pr3+, or Gd3+codoped Ce:YAG single crystals were grown by using the Czochralski method. The photoluminescence(PL) emission and excitation spectra and transmittance were measured and investigated. The additional red-emitting bands were observed in the PL emission spectra of Eu,Ce:YAG and Pr,Ce:YAG single crystals and the formation of noticeable peaks was studied with reference to the schematic energy level diagrams. A red-shifted phenomenon was observed in the PL emission spectrum of Gd,Ce:YAG. With codoped Eu3+, Pr3+, or Gd3+ions, warmer white light was achieved for the white light emitting diodes and the color rendering index became higher.     

Self-sum- and -difference-frequency mixing in GdAl(3)(BO(3))(4):Nd(3+) for generation of tunable ultraviolet and infrared radiation

We exploited Nd(3+) laser emission at 1061.9 nm ((4)F(3/2)?(4)I(11/2) channel) in a self-chi((2)) active GdAl(3)(BO(3))(4):Nd(3+) laser crystal. UV radiation was obtained from a 1.8% yield from self-sum-frequency mixing: 1/pump + 1/1061.9 = 1/UV, during pumping in the Nd(3+) (4)G(5/2)-(2)G(7/2) levels near 588 nm. The UV tunability had a range of 378-382 nm. We have demonstrated, for the first time to our knowledge, generation of coherent IR radiation from a self-difference-frequency mixing laser: 1/pump - 1/1061.9 = 1/IR. We got a 0.5% yield and tunability in the 1305-1365-nm range.     

Pr^3＋在氟化物玻璃（ZBLAN）中的能级和光学吸收特性

通过实验测量了Ｐｒ＾３＋在氟化物玻璃中的光学吸收，根据Ｊｕｄｄ－Ｏｆｅｌｔ理论计算了Ｐｒ＾３＋离子的振子强度，辐射跃迁几率，分支比等光谱参数。并通过对能级的拟合，给出了Ｐｒ＾３＋在玻璃介质中的Ｓｌａｔｅｒ参数，自旋－轨道耦合和电子组态相互作用参数。     

Tm~(3+)/Yb~(3+)∶LaF_3纳米体系中掺杂Yb~(3+)离子对Tm~(3+)离子荧光发射的影响

为研究Yb~(3+)离子浓度变化对Tm~(3+)离子在蓝色波段荧光强度的影响,以NaF和La(NO_3)_3为原料,采用水热法制备了Tm~(3+)和Yb~(3+)共掺的Tm~(3+)/ Yb~(3+)∶LaF_3纳米颗粒.用X射线衍射对LaF_3纳米颗粒进行表征的结果显示,纳米晶体结构呈六方相.透射电镜的观测结果显示,纳米颗粒样品大小均匀、分散性良好.在波长为800 nm的激光激发下,观测到了上转换蓝光发射,其中包括波长为474 nm和479 nm的较强的荧光辐射(相应的跃迁为~1G_4→~3H_6)和波长位于450 nm的强度较弱的荧光发射(相应的跃迁为~1D_2→~3F_4).通过观测不同Yb~(3+)离子浓度条件下共掺Tm~(3+)/Yb~(3+)∶LaF_3样品的荧光光谱,研究了Yb~(3+)离子掺杂浓度对于Tm~(3+)离子的荧光发射的影响,并探讨了产生这种现象的原因.研究结果显示,对于~1G_4→~3H_6跃迁产生的荧光发射(474 nm),当Yb~(3+)离子浓度增大时,反向能量传递速率的增加导致了荧光强度的增大.然而,当Yb~(3+)离子浓度增大到一定程度时,Yb~(3+)离子激发态能级寿命的减少将引发荧光强度的下降.相比较而言,Yb~(3+)离子的浓度的变化对于~1D_2→~3F_4跃迁产生的位于450 nm处荧光强度的影响较弱.     

Eu~(3+)作探针研究铋铕共掺硼硅酸盐玻璃光学特性

利用高温烧结法制备了铕/铋铕共掺硼硅酸盐玻璃系列样品,测量了样品的激发光谱、发射光谱和声子边带谱,利用Eu3+离子作为探针进一步研究了敏化剂Bi3+的掺入对Eu3+发光的影响.结果表明:本文制作的玻璃样品的电子-声子耦合系数比以往报道过的硼铅等玻璃材料的值都要小,但在硼硅酸盐玻璃中掺入Bi3+会使Eu3+的无辐射跃迁概率增加;Bi3+对Eu3+有敏化作用,Bi3+的掺入使材料的共价性增强,对称性降低,这又使得Eu3+的发光整体变强.所以,在硼硅酸盐玻璃体系中,Eu3+发光的增强不仅仅是由于Bi3+对Eu3+的能量传递,而是以上各因素综合作用的结果.     

稀土（La^3＋,Pr^3＋）—DBS—偶氮胂有色配合物组合和稳定常数的吸收光谱法测定

稀土（Ｌａ＾３＋,Ｐｒ＾３＋）在酸性条件下与ＤＢＳ－偶氮胂发生配位反应,首先对光谱数据进行因子分析法处理从而判断出只生成一类配合物,进而采用线性回归法计算配合物组成,摩尔吸光系数,表观稳定常数及配位体浓度,实验结果表明,在１ｍｏｌ．Ｌ＾－１ＨＣｌ介质中,Ｌａ＾３＋、Ｐｒ＾３＋与ＤＢＳ－偶氮胂形成Ｍ：Ｌ＝１：３的配合物,其摩尔吸光系数分别为１．３９９＊１０＾５和１．１５１７＊１０＾５Ｌ．ｍｏｌ＾－１．ｃｍ＾－１,表观稳定常数ｌｏｇβ３分别为１５．３６和１５．３４。     

硼酸镁中Ce^3＋,Gd^3＋对Dy^3＋发光的敏化作用

本文研究了铈、钆、镝激活硼酸镁的激发光谱、发射光谱、发光寿命和能量传递过程。     

(La,Ce,Tb)BO3的合成及光谱性质

采用高温固相法合成了(La,Ce,Tb)BO₃绿色发光粉,并对该发光粉进行了XRD和SEM分析。结果表明:(La,Ce,Tb)BO₃的晶体结构和LaBO₃相同,Ce³⁺、Tb³⁺的掺入并没有改变晶体的结构,发光粉颗粒大小均匀,形貌规则,粒度在5 μm左右。研究了(La,Ce,Tb)BO₃的光谱性质,在(La,Ce,Tb)BO₃的发射和激发光谱中除了有Tb³⁺的特征发射和激发峰外,还有Ce³⁺的特征发射和激发峰。比较了(La,Ce)BO₃发射光谱和(La,Tb)BO₃的激发光谱,两者存在重叠,这为Ce³⁺→Tb³⁺的能量传递提供了条件。将(La,Ce,Tb)BO₃的发射光谱与商品粉(La,Ce,Tb)PO₄进行比较,两者的发射主峰都在541 nm处, (La,Ce,Tb)BO₃在489 nm处的峰位稍有红移,通过计算表明,(La,Ce,Tb)BO₃的发光亮度达到商品粉(La,Ce,Tb)PO₄的94.7%。因此,(La,Ce,Tb)BO₃是一种很有应用前景的绿色发光粉。