稀土粉末Eu∶Y_2O_3的自由感应衰减量子拍

稀土固体是重要的激光和光电子材料。目前 ,由于以宽带信号和太赫兹比特数据传输率为特征的信息技术的发展 ,稀土固体材料的相干瞬态动力学过程成为宽带与高速信息光子学的基本物理问题之一。研究了室温下稀土粉末样品Eu3+ ∶Y2 O3自由感应衰减的相干瞬态光谱 ,这有助于理解有效的光吸收动力学、激发态弛豫、相干能量传递和超短光脉冲在稀土固体中的传播。用一对紫外飞秒相干光脉冲作用于稀土粉末样品Eu3+ ∶Y2 O3,然后监测物质激发态的布居数随两个激发脉冲之间的延时的变化 ,测量到其自由感应衰减量子拍 (FID) ,从拍频周期分析确定了其能级精细结构 ,能级的退相时间长达皮秒量级。理论分析和实验结果符合得很好。对稀土离子的量子干涉的研究 ,表明其在受激受控光放大方面具有潜在的应用前景     

二氧化硅包覆稀土配合物Eu(TTA)3phen制备及其荧光性能研究

将稀土配合物Eu(TTA)3phen分散于异丙醇中,通过水解正硅酸乙酯(TEOS)的方法制备了新型荧光材料二氧化硅包覆稀土配合物SiO2/Eu(TTA)3phen.荧光光谱表明二氧化硅包覆后的稀土配合物荧光强度增加了将近一倍,同时,发现Eu3+在617.4 nm附近的发射峰变得非常尖锐,而未经二氧化硅包覆的Eu(TTA)3phen在617.4 nm附近只是非常不明显的肩峰.这说明了二氧化硅包覆稀土配合物后,Eu(TTA)3phen的结构变得更加刚性化,从而使得荧光强度增强.荧光寿命实验结果表明二氧化硅包覆后的稀土配合物寿命减少,这正是由于稀土配合物分子结构刚性化造成的.     

Ce3+离子敏化Eu3+∶Cr3+∶Sm3+∶YAG外延层的荧光现象

对Ce3+ ∶Eu3+ ∶Cr3+ ∶Sm3+ ∶YAG处延层中的荧光敏化现象进行了报道和分析 ,在较高浓度的Ce3+ 离子掺杂时 ,外延层在蓝色、绿色波段出现了新的荧光谱线 ,可解释为在Ce3+ 离子敏化作用下 ,Eu3+ 离子产生了由高位激发态能级5Di(i=1,2 ,3)直接到基态能级7Fj(j =0 ,1,2 ,3)的辐射跃迁过程 ,并且这种Ce3+ ∶Eu3+ ∶Cr3+ ∶Sm3+ ∶YAG外延层还是一种新颖的白色单晶荧光材料。     

SmxLa1-xP5O14和DyxY1-xP5O14晶体的荧光寿命研究

本文用脉冲衰减法和时间分辨荧光光谱法测量了六种不同稀土离子浓度的SmxLa1-xP5O4晶体的4G5/2→6HJ(J=5/2,7/2,9/2,11/2)四个能级和七种不同稀土离子浓度的DyxY1-xP5O14晶体的4F9/2→6HJ(J=15/2,13/2,11/2,9/2)四个能级的荧光寿命和荧光强度。结果指出,在这类晶体中,Sm3+和Dy3+的荧光寿命随着离子的浓度增加而变短,存在着严重的荧光浓度猝灭现象。最后还讨论了浓度与寿命,寿命与荧光强度的关系。     

共掺杂对Y_2O_3:Eu~(3+)纳米晶结构和发光性质的影响

采用燃烧法制备不同离子(M:Li+,Na+,K+,Mg2+,Sr2+,Ba2+,B3+,Al3+)共掺杂的纳米Y2O3∶Eu3+粉末。系统地研究了各掺杂离子对纳米Y2O3∶Eu3+材料的结构、发光性质及其寿命的影响。比较发现,掺杂不仅可以调节纳米材料的尺寸,还可以影响材料的结晶性,尤其是后者对发光性质和荧光动力学过程,如荧光强度、电荷迁移带的位置和5D0的寿命等有重要的影响。     

Tb~(3+)和Yb~(3+)掺杂Y_2O_3发光粉体的制备和近红外量子剪裁研究

采用共沉淀法制备了Y2O3∶Tb3+和Y2O3∶Tb3+,Yb3+两种样品。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)和荧光光谱仪分析和测试了样品的形貌、微结构和室温下的荧光光谱,得到了不同掺杂浓度、退火温度、溶液pH值下Y2O3∶Tb3+的最优工艺制备条件:Tb3+浓度1.5%、退火温度1 400℃、溶液偏碱性环境下,样品在300nm光激发下于543nm处有最大绿光发射。详细分析了Tb3+能级结构和跃迁属性与实验光谱的对应关系,阐述了工艺条件的影响机理和主要影响样品发光的荧光猝灭效应。制备的Y2O3∶Tb3+,Yb3+粉体,敏化离子Tb3+与激活离子Yb3+间存在能量传递过程,使样品在近红外区有可观的发光,从能级角度对两离子间的合作下转换发光过程进行了描述,同样分析了该体系下的荧光猝灭过程。实验证明近红外量子剪裁可有效提高掺杂离子的发光效率,在硅太阳能电池等领域有广阔的应用前景。     

Sr_(1-y)Eu_ySi_2O_(2-z)N_(2+2z/3)的发光性质及其在白光LED上的应用

采用高温固相法合成出系列黄绿色Sr1-yEuySi2O2-zN2+2z/3荧光材料,进行了光学性质表征并探索了其在LED上的应用。在Eu2+掺杂浓度为0～0.200范围内,所合成的化合物为系列色坐标可调的黄绿光-黄光连续固溶体,在250～500nm具有高的激发效率,激发和发射光谱位置及其发射强度随Eu2+浓度改变产生规律性变化;利用光谱理论系统研究了Eu2+的最低5d吸收能级、5d轨道重心移动、晶体场分裂和Stokes位移对激发和发射光谱位置、半峰全宽和荧光寿命的影响及其相互关系。该类荧光材料在77～425K具有良好的温度特性,425K时的发射强度为77K的58%左右。首次将它们和近紫外LED(～400nm)、蓝光LED(～460nm)封装成高亮度黄绿光和黄光LED以及白光LED,发光效率高达19lm/W,这些封装的LED的发光性能也随着Eu2+浓度,以及粉胶比例变化而呈规律性变化。     

变温下Y2O3∶Eu3+纳米晶的荧光光谱和动力学过程

通过分析影响Y2O3:Eu3+在488nm激光激发下的5D0→7F2变温荧光发射强度的因素,建立起公式并对实验数据进行拟合,得到纳米晶的温度猝灭速率大于体材料的温度猝灭速率.测得Y2O3:Eu3+纳米晶和体材料的5D0→7F2发射峰的变温线宽,通过内应力和量子限域效应对其不同进行了解释.测量了Y2O3:Eu3+在共振激发下的5D0能级的荧光衰减时间随温度的变化,又利用公式对其进行拟合,得出了相比于体材料,纳米晶的辐射跃迁速率和无辐射跃迁速率均增大,但量子效率变小的结论.然后利用晶格畸变和表面态效应对上述结 关键词： 温度猝灭 Y2O3:Eu3+纳米晶 荧光衰减 线宽     

变温下Y2O3∶Eu3+纳米晶的荧光光谱和动力学过程

通过分析影响Y2O3: Eu3+在488nm激光激发下的5D0→7F2变温荧光发射强度的因素,建立起公式并对实验数据进行拟合,得到纳米晶的温度猝灭速率大于体材料的温度猝灭速率.测得Y2O3: Eu3+纳米晶和体材料的5D0→7F2发射峰的变温线宽,通过内应力和量子限域效应对其不同进行了解释.测量了Y2O3: Eu3+在共振激发下的5D0能级的荧光衰减时间随温度的变化,又利用公式对其进行拟合,得出了相比于体材料,纳米晶的辐射跃迁速率和无辐射跃迁速率均增大,但量子效率变小的结论.然后利用晶格畸变和表面态效应对上述结论进行了解释.     

Eu3+配合物掺杂聚合物的制备与光谱性能研究

以噻吩甲酰三氟丙酮(2-thenoyltrifluoroacetone , TTFA), 六氟乙酰丙酮(hexafluoro- acetylacetone, HFA)和甲基联苯甲酰(dibenzoylmethide, DBM) 分别为配体合成了Eu3+的三种β-二酮类配合物Eu(TTFA)3、Eu(HFA)3和 Eu(DBM)3,以及掺杂这三种配合物的聚合物（聚甲基丙烯酸甲酯,PMMA）,并用分光光度计对它们的荧光光谱特性进行了分析研究.结果表明,三种配合物中Eu(TTFA)3荧光强度最强,并分析了其原因,发现能级匹配、配体取代基、配体结构对称性等均对配合物发光效率有重要的影响.通过比对,证明了TTFA是Eu3+发红色荧光的优良配体.进一步研究还发现,Eu(TTFA)3掺杂PMMA中稀土离子的荧光强度和荧光寿命均随掺杂浓度（质量分数为0.08～0.5）的增加而增大.     

Synthesis and luminescence of a novel conjugated europium complex with 6-parachloroaniline carbonyl 2-pyridine carboxylic acid

A novel organic ligand, 6-parachloroaniline carbonyl 2-pyridine carboxylic acid, and the corresponding europium complex, tris(6-parachloroaniline carbonyl-2-pyridine carboxylate) europium (III) have been designed and synthesized. The results showed that the synthesized product was a conjugated complex, emitting remarkable strong red luminescence, and was a good red luminescence material with good thermal stability. The ⁵D₀ lifetime of Eu³⁺ in the complex was examined using time-resolved spectroscopic analysis. The lifetime values for 1.0×10⁻⁵ mol/l ethanol solution of the complex and for the complex solid were 0.49±0.01 and 1.94±0.01 ms, respectively.     

Hartmagnetische Legierungen der Seltenen Erdmetalle mit 3d-Metallen

The phase relations obtained from alloys of the rare-earth metals (RE) with 3d-metals are initially discussed, as well as the crystal structures and the general physical properties of the corresponding intermetallic compounds. The magnetic properties of RE-3d-compounds and the essential data of a hard-magnetic material are then summarized. The different steps in the production of RE-Co-permanent magnets are reviewed in relation to the underlying basic physical mechanisms. Finally, other possible hard-magnetic RE-3d-alloys and some general trends of physical and metallurgical investigations, necessary for the improvement of the RECo₅-magnets, are outlined.

     

Pressure induced phase transition in rare earth mono-antimonides

Pressure induced structural phase transition of mono-antimonides of lanthanum, cerium, praseodymium and neodymium (LnSb, Ln=La, Ce, Pr and Nd) has been studied theoretically using an inter-ionic potential with modified ionic charge which parametrically includes the effect of Coulomb screening by the delocalized f electrons of rare earth (RE) ion. The anomalous structural properties of these compounds have been interpreted in terms of the hybridization of f electrons with the conduction band and strong mixing of f states of Ln ion with the p orbital of neighbouring antimonide ion. All the four compounds are found to undergo from their initial NaCl (B₁) phase to body centered tetragonal (BCT) phase at high pressure and agree well with the experimental results. The body centered tetragonal phase is viewed as distorted CsCl structure and is highly anisotropic with c/a=0.82. The transition pressure of LnSb compounds is observed to increase with decreasing lattice constant in NaCl phase. The nature of bonds between the ions is predicted by simulating the ion-ion (Ln-Ln and Ln-Sb) distances at high pressure. The calculated values of elastic constants are also reported.     

稀土配合物Eu(asprin)_3phen发光特性的研究

将稀土配合物Eu(asprin)_3phen掺杂到导电聚合物PVK中,制成结构分别为ITO/PVK:RE配合物/LiF/AI(1),ITO/PVK:RE配合物/PBD/LiF/AI(2)的电致发光(EL)器件。发现二者的电致发光谱存在着较大的差别:在器件(1)中,来自Eu~(3 )的位于594nm(~5D_0→~7F_1)和614nm(~5D_0→~7F_2)处的发光强度大致相当,而在器件(2)中,EL主要来自Eu~(3 )位于614nm的发光,594nm处的发光很弱,与薄膜状态下的光致发光谱(PL)一致。并针对此现象进行了初步讨论。     

Ion sputtering of minerals and glasses: a first step to the simulation of solar wind erosion

Selected rockforming minerals (plagioclase, augite, olivine, ilmenite, silicate and metal phases of the meteorite “Brenham”) as well as silicate and phosphate glasses were irradiated with heavy ions (⁴He⁺, ¹⁴N+, ²⁰Ne⁺, ⁴⁰Ar+, ⁵⁶Fe+, Xe⁺ _nat) in the energy range of 50-130 keV in order to study ion-induced sputtering. Sputtering yields were measured independently by means of multiple beam interferometry and particle track autoradiography.

The theory of sputtering by Sigmund, modified by Smith, was used to convert experimental heavy ion sputtering yields to H⁺- and He⁺-sputtering yields of the same target. Taking into account solar wind irradiation conditions at the lunar surface, an estimate of lunar erosion rates due to solar wind sputtering is given for the targets studied.     

稀土配合物Eu(asprin)3phen发光特性的研究

将稀土配合物Eu(asprin)3phen掺杂到导电聚合物PVK中，制成结构分别为ITO/PVK：RE配合物／LiF／Al(1)，ITO／PVK：RE配合物／PBD/LiF/Al(2)的电致发光(EL)器件。发现二者的电致发光谱存在着较大的差别：在器件(1)中，来自Eu^3 的位于594nm(^5D0→^7F1)和614nm(^5D0→^7F2)处的发光强度大致相当，而在器件(2)中，EL主要来自Eu^3 位于614nm的发光，594nm处的发光很弱，与薄膜状态下的光致发光谱(PL)一致。并针对此现象进行了初步讨论。     

稀土元素的X射线荧光光谱分析

近十年来,国内外的稀土元素X射线荧光光谱分析工作有了很大进展。随着稀土应用的日益广泛,XRF不仅是常量稀土分析手段,也已用于微量和痕量稀土分析。本文着重在样品的预富集,制样技术,仪器条件,校正谱线干扰以及消除基体效应的数学校正法等方面做了阐述。     

Luminescence properties of Eu- and Mg-doped LiTaO3 obtained via the polymeric precursor method

This work reports the pure lithium tantalate (LiTaO₃), europium (III)-doped LiTaO₃ and magnesium (II)-europium (III)-doped LiTaO₃ preparation by the polymeric precursor method, using four different powered samples of Eu³⁺ ion concentrations 0.1 and 1 at%, observing their effect on the luminescent property of the material. Results indicated LiTaO₃ phase free of secondary phases at 650 °C and the photoluminescence (PL) emission spectra showed the characteristic sharp emission bands given by Eu³⁺ ions when they are excited at a wavelength of 399 nm. An increase of dopants led us to a non-homogeneous broadening and showed a slightly larger one when Mg was added. A displacement of the transition ⁵D₀→⁷F₀ to shorter wavelengths as function of Eu³⁺concentration was also noticed.     

Magnetocaloric effect in the binary intermetallic compound DySi

Polycrystalline binary rare earth intermetallic compound DySi is found to be dimorphic at room temperature (orthorhombic FeB type, space group Pnma, No. 62 and CrB type, space group Cmcm, No. 63). This compound exhibits interesting magnetic properties including an antiferromagnetic transition at ∼38 K (T_N) and a low-temperature field-induced transition in a critical field of 65 kOe, at 5 K. The values of magnetic entropy change and adiabatic temperature change near the magnetic transition in DySi have been estimated using the heat capacity data obtained in different applied fields. Negative magnetocaloric effect is observed at temperatures close to and below T_N, in fields up to 50 kOe.     

Eu（Sm）－DBM－CPB体系的激光感生时间分辨荧光光谱的研究

用自装的激光感生时间分辨荧光光谱装置，研究了Ｅｕ、Ｓｉｎ－二苯甲酰甲烷（ＤＢＭ）体系在阳离子表面活性剂溴代十六烷基吡啶（ＣＰＢ）存在下的光谱特性和荧光衰减动力学特性。给出同时测定Ｅｕ和Ｓｉｎ的激光感生时间分辨荧光光谱分析方法，用于高纯氧化物中痕量Ｅｕ和Ｓｉｎ的测定，获得了满意的结果。