Structure and electrical properties of Pr ans Sm doped CeO2 and Ce2MoO15 based solid electrolytes

Sin and Pr doped CeO2 and Ce6MoO15 based materials were synthesized by sol-gel method. The structure of the powders were characterized by X-ray diffraction (XRD), Raman spectra, field emission scanning electron microscopy(FE-SEM) and the electrical conductivity of the samples was investigated by AC impedance spectroscopy. By comparing the structure and electrical properties of different systems, it could be concluded that the electrical property of Ce6MoO15 based system is better than that of CeO2 system. The added Mo element resulted in the increase of gain size and improved the grain boundary conductivity notably below 600 degrees C, while the Pr dopant induced the smaller grain size and improved the grain boundary conductivity of the materials.

Sm~(3+)对甲醇电化学氧化反应的助催化作用

分别以相同面积的光滑 Pt电极和吸附了 Sm3+ 的铂电极作为工作电极 ,在酸性介质中采用循环伏安法对甲醇氧化进行测定 .结果表明 ,吸附了 Sm3+ 的 Pt电极上产生了更大的氧化电流 ,表明 Sm3+ 的加入对甲醇的电催化氧化起到了促进作用 .这一研究结果在直接甲醇燃料电池 ( DMFC)阳极催化剂研制方面具有较大的应用潜力

Y_2O_2S:Sm~(3+)发光材料在不同激发波长的浓度特征

研究了在不同激发波长下三价钐离子掺杂硫氧化钇的发光强度对浓度的依赖关系。研究发现磷光体的发光强度不仅跟激活离子的浓度有关,而且跟激发时所采用的不同激发波长有关。磷光体发光强度与激活剂掺杂量的变化曲线表明,在不同激发路径下磷光体具有不同的发光性质。采用Sm3+离子直接跃迁的413nm对样品进行激发时,发生猝灭的浓度低至约02mol%;当采用263nm高能紫外线激发时,浓度猝灭发生在较高浓度处(～2mol%),后者是前者的10倍。对Sm3+离子发射强度与浓度关系曲线进行了拟合计算,结果表明Sm3+在Y2O2S中浓度猝灭的原因主要是相邻中心的偶极四极相互作用引起的交叉弛豫。

新型橙红色长余辉发光材料Gd_2O_2S:Sm~(3+)的合成

采用固相反应法合成了一种新型的橙红色长余辉磷光粉 Gd2 O2 S:Sm3 + ,并用全自动 X射线粉末衍射仪表征了其结构 ,用荧光光谱仪测试了其激发、发射光谱、余辉光谱和余辉衰减曲线。 XRD证实其为单相的硫氧化钆。该磷光体呈现 Sm3 +的三个特征发射 (4G5/2 → 6HJ,J=5 /2 ,7/2 ,9/2 )。经紫外或可见光激发后能观察到长时间明亮的余辉发光。

Energy transfer and upconversion luminescence properties of Y2O3 : Sm and Gd2O3 : Sm phosphors

Y2O3:Sm and Gd2O3:Sm powder phosphors were prepared by carbonate coprecipitation method. The purified crystalline phases of Y2O3:Sm and Gd2O3:SM were obtained at 600degreesC, and the crystallinity increases with increase in annealing temperature. Both samples contain aggregated phosphor particles. An energy transfer (ET) from Y2O3 and Gd2O3 hosts to sm(3+) has been observed, and the ET efficiency in the latter is higher than that in the former because an energy migration process like Gd3+-(Gd3+)(n)-Sm3+ has occurred in the latter. Furthermore, an upconversion luminescence from the (4)G(5/2) level of Sm3+ has been observed in both Y2O3 and Gd2O3 under the excitation of 936 nm infrared, whose mechanisms are proposed. Both the up and downconversion emission intensities of Sm3+ in Gd2O3 are stronger than those in Y2O3.

一种新的橙红色长余辉荧光材料Y_2O_2S∶Sm~(3+)

铜激活的硫化锌 (Zn S∶ Cu)和铕激活的硫化钙 (Ca S∶ Eu)是最早获得应用的蓝色和红色长余辉材料 .随后 ,相继发现了铝酸盐体系和硅酸盐体系两大类长余辉荧光材料 [1～ 3 ] .这两类长余辉荧光材料在发光亮度、余辉时间、稳定性方面都较前述硫化物系列长余辉荧光材料有很大提高 ,从而具有非常广阔的应用前景和应用范围 [4～ 6] .但这两类长余辉荧光材料的发光颜色一般为蓝紫、蓝或黄绿 ,没有红色发光现象 .随着研究的深入 ,人们发现了稀土元素激活的碱土钛酸盐红色长余辉荧光材料 ,这种荧光材料在发光亮度及余辉上都有明显的提高 [7,8] ,而且解决了硫化物不稳定的缺点 .近年来才发展起来的以碱土金属氧化物为发光基质 ,以 Eu3 + 为激活剂的红色长余辉荧光材料进一步提高了余辉亮度及时间 [9] .传统碱土硫化物类磷光体有较宽的激发谱带 ,可在不同的光源下激发 .但它的稳定性较差 ,必须进行工艺后处理才能得到应用 .其它几类磷光体的激发光源谱带较窄 ,仅限于紫外光源 ,因此使其应用范围受到限制 .目前已报道的各种长余辉红色荧光材料在余辉时间方面有较大的差异 ,从十几分钟到几百分钟不等 ,各类红色磷光...

稀土Sm对于Cu/Zr基合成醇催化剂的改性作用

中国科学院山西煤炭化学研究所

Local structure and valences of samariurn in SrB4O7 : Sm and SrB6O10 : Sm prepared in-air

The coordination numbers for the samarium atoms and the Sm-O bond distances in SrB4O7:Sm and SrB6O10:Sm prepared in air were determined by means of Sm-L-3 edge EXAFS. The coordination. was found to be nine-folded for both these hosts and the bond distance was 2.40-2.42 Angstrom in SrB4O7:Sm and 2.42-2.44 Angstrom in SrB6O10:Sm. For SrB4O7:Sm the coordination number is coincident with that of the strontium. atoms suggesting the substitution of the samarium atoms at the strontium sites. The coordination number of the strontium atoms in SrB6O10 was also suggested to be nine assuming the same type of substitution. The valences of samarium were determined from the luminescent spectra. Both divalent and trivalent ions were present in both SrB4O7:Sm and SrB6O10:Sm, while the fraction of Sm2+ was higher in the former than in the latter. This difference has been assigned to the difference in rigidity between the B-O networks in these structures.

Synthesis-dependent luminescence properties of Y3Al5O12 : Re3+ (Re=Ce, Sm, Tb) phosphors

By using metal nitrates and oxides as the starting materials, Y2Al5O12 (YAG) and YAG:Re3+ (Re = Ce, Sm, Th) powder phosphors were prepared by solid-state (SS), coprecipitation (CP) and citrate gel (CG) methods. The resulting YAG and YAG-based phosphors were characterized by XRD, FT-IR, SEM and photoluminescent excitation and emission spectra. The purified crystalline phases of YAG were obtained at 800 degreesC (CG) and 900 degreesC (CP, SS). At an identical annealing temperature and doping concentration, the doped rare-earth ions showed the stronger emission intensity in the CP- and SS-derived phosphors than the CG-derived YAG phosphors. The poor emission intensity for the CG-derived phosphors is mainly caused by the contamination of carbon impurities from citric acid in the starting materials.

UV-VUV excited luminescence of SrBPO5 : Sm phosphor prepared in air

The high-resolution luminescent spectrum of divalent samarium excited by 355 nm UV light at 77 K, the VUV excitation spectra, the VUV excited emission spectra and EXAFS at Sm-L-3 edge were reported for samarium doped strontium borophosphate, SrBPO5:Sm prepared by solid state reaction in air at high temperature. The high-resolution luminescent spectrum showed that the divalent samarium ions occupied the C-2upsilon lattice sites. The VUV excitation spectra indicated that the sample exhibited absorption bands with the maxima at 129 and 148 nm, respectively. The performance of EXAFS at Sm-L3 absorption edge suggested that the samarium ions were nine-coordinated and the mean distances of bond Sm-O were 2.38 Angstrom.

Crystal structure of a luminescent complex Sm(HTH)(3)Phen

The crystal structure of Sm(HTH)(3)Phen [HTH: 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)-1,3-hexanedione, Phen: 1,10-Phenanthroline] has been determined by single crystal X-ray diffraction and the coordination geometry of Sm atom is a dodecahedron. The complex can give the characteristic luminescence of Sm3+ upon UV excitation.

Syntheses and crystal structures of bis(tetrahydrofurfurylindenyl) lanthanocene chlorides (C4H7OCH2C9H6)(2)LnCl (Ln = Nd, Sm, Dy, Ho, Er, Yb)

Reaction of anhydrous lanthanide trichlorides with tetrahydrofurfuryl indenyl lithium in THF afforded bis(tetrahydrofurfurylindenyl) lanthanocene chlorides complexes (C4H7OCH2C9H6)(2) LnCl, Ln = Nd (1), Sm (2), Dy (3), Ho (4), Er (5), Yb (6). The X-ray crystallographic structures of all the six complexes were determined and these indicate that they are unsolvated nine-coordinate monomeric complexes with a trans arrangement of both the sidearm and indenyl rings in the solid state. They belong to the same crystal system (orthorhombic) and space group (P2(1)2(1)2(1)) with the same structure. Especially, they are more stable to air and moisture than the corresponding unsubstituted indenyl lanthanide complexes.

La_2O_3∶Sm发光粉的合成与发光性质的研究

以La2O3和Sm2O3为原料,用碳酸盐沉淀法制备了La2O3:Sm3+发光粉,并分别用XRD,SEM和发光光谱及寿命进行了表征。La2O3晶相的形成温度为800℃,其发光强度随温度升高而增强。La2O3基质中Sm3+的最佳掺杂浓度为1.5%(摩尔分数)。

YAG∶Nd中Pr,Sm,Dy杂质对其光谱的影响

采用溶胶 -凝胶法合成了YAG∶Nd ,Re(Re =Pr,Sm ,Dy)系列化合物 ,研究了它们的光谱性质 .结果表明 :Pr3 + ,Sm3 + ,Dy3 + 对YAG基质中Nd3 + 的发光具有猝灭作用 ,属于有害杂质 ,在激光晶体原料中必须除去

TG-DTA properties of new nonlinear optical materials: K(2)Ln(NO3)(5)center dot 2H(2)O (Ln = La, Ce, Pr, Nd, Sm)

Single crystals of K(2)Ln(NO3)(5). 2H(2)O (KLnN) (Ln = La, Ce, Pr, Nd, Sm) were grown from aqueous solution. The thermogravimetric analysis and differential thermal analysis curves of KLnN demonstrate that the processes of dehydration, melting, irreversible phase transformation and decomposition of NO3- take place in sequence in the heating processes (except KCN). There are three stages in the decomposition of NO3- in KLnN (Ln = La, Nd, Sm) while two in KLnN (Ln = Ce, Pr). K(2)Ln(NO3)(5) is formed at about 225 degrees C by the reaction of KNO3 and Ln(NO3)(3). nH(2)O (Ln = La, Ce, Pr, Nd). (C) 2000 Elsevier Science Ltd. All rights reserved.