光电化学反应的催化I.大颗粒金岛对n-TiO2电极上光电化学过程的催化作用

用溅射、光还原及电沉积法在n-TiO2单晶电极表面上形成了大颗粒金岛,测量了这些电极和纯金电极在H2SO4溶液以及含有Fe[3+]/Fe[2+]的酸溶液中的光电化学极化行为。通过分析和比较这些曲线,确定了大颗粒金岛与n-TiO2单晶的接触具有欧姆结性质。并借助于可换盘旋转环盘电极,在含Ce[3+]的酸溶液中测量了裸TiO2电极及载金TiO2电极上Ce[3+]的竞争光电化学氧化。证实了以大岛形式在TiO2电极表面上分布的催化剂只能催化暗反应,而不能催化光电化学反应。     

Nd3+掺杂PbWO4晶体的光谱特征和浓度效应

钨酸铅晶体(PbWO4)是新型的闪烁晶体,针对其广阔的光电子应用,实验测试了Nd3 掺杂PbWO4晶体的吸收光谱,讨论了不同的Nd3 掺杂浓度对于吸收系数和PbWO4光学吸收边的影响。依据Judd-Ofelt理论计算了吸收截面积、强度参数、量子荧光效率、荧光分支比等。讨论了不同浓度Nd3 掺杂的PbWO4晶体的光致发光光谱;室温LD808nm泵浦下,1.06μm荧光发射的荧光强度、荧光寿命和发射截面积,论述了这些性能随Nd3 掺杂浓度的变化关系。     

TEMPERATURE EFFECT ON LOW-CYCLE FATIGUE BEHAVIOR OF NICKEL-BASED SINGLE CRYSTALLINE SUPERALLOY

The low-cycle fatigue （LCF） behavior of a nickel-based single crystal superalloy with [001] orientation was studied at an intermediate temperature of T0℃ and a higher temperature of To ＋ 250℃ under a constant low strain rate of 10^-3 s^-1 in ambient atmosphere. The superalloy exhibited cyclic tension-compression asymmetry which is dependent on the temperature and applied strain amplitude. Analysis on the fracture surfaces showed that the surface and subsurface casting micropores were the major crack initiation sites. Interior Ta-rich carbides were frequently observed in all specimens. Two distinct types of fracture were suggested by fractogaphy. One type was characterized by Mode-I cracking with a microscopically rough surface at To ＋ 250℃. Whereas the other type at lower temperature T0℃ favored either one or several of the octahedral {111} planes, in contrast to the normal Mode-I growth mode typically observed at low loading frequencies （several Hz）. The failure mechanisms for two cracking modes are shearing of γ＇ precipitates together with the matrix at T0℃ and cracking confined in the matrix and the γ/γ＇interface at To - 250℃.     

Isolation and Identification of New Impurities in Nomegestrol Acetate

Three new and five known steroidal compounds as impurities in nomegestrol acetate(I) were isolated from the enriched mother liquor via various chromatographic methods. Their structures were elucidated by spectrometric analysis and single-crystal X-ray diffraction analysis. New compounds were characterized as 17α-hydroxyl-3-oxoes-trane-5β,17-dicarbonitrile(1), 4-ethyl-17α-hydroxyl-3-oxoestr-4-en-17-carbonitrile(2), 4-ethylestr-4-en-3,17-dione(3). The 13C NMR data of known estrane derivatives(4―7) were also r...     

片状ZnO单晶的光电性能研究

通过SEM、TG、XRD、IR、UV-Vis研究了用均匀沉淀法制备的片状ZnO单晶的结晶学和光电性能.结果显示:片状ZnO是结晶良好的晶体,属纤锌矿结构,对中红外和可见光透射率很高,达80;以上,而对近紫外光的透射率仅为6;.片状ZnO单晶的晶格常数为a＝0.3246 nm,c＝0.5207 nm,禁带宽度为3.25 eV.     

不同掺杂浓度Tm3+：LiLuF4单晶的1800 nm荧光发射

采用坩埚下降法生长了Tm³⁺掺杂浓度为0.45%,0.90%,1.63%与3.25%（摩尔分数,x）的LiLuF₄单晶.测试了样品的电感耦合等离子体原子发射光谱（ICP-AES）、X射线衍射（XRD）谱、吸收光谱（1400-2000 nm）,并且分析比较了808 nm半导体激光器（LD）激发下荧光光谱. 结果表明：当Tm³⁺的浓度从0.45%变化到3.25%时,1800 nm处的荧光强度呈现了先增后减的趋势,当掺杂浓度约为0.90%时达到最大值,而位于1470 nm处的荧光强度则呈现了相反的趋势. Tm³⁺：³F₄能级的荧光衰减寿命随着掺杂浓度的增加不断减小. 1800 nm处的这种荧光强度变化归结于Tm³⁺离子间的交叉驰豫效应（³H₆,³H₄→³F₄,³F₄）和自身的浓度猝灭效应. 同时计算得到了浓度为0.90%的样品在1890 nm处的最大发射截面为0.392×10^-20 cm². 并且根据Judd-Ofelt 理论所得寿命和测定的荧光寿命计算得到了³F₄→³H₆的最大量子效率约为120%.     

1,4-二(3,4-二甲氧基苯巯基)丁烷Ag(Ⅰ)配合物的合成和单晶结构

1;4-二(3;4-二甲氧基苯巯基)丁烷Ag(Ⅰ)配合物的合成和单晶结构;二(二甲氧基苯巯基)丁烷;Ag(Ⅰ)配合物;晶体结构;一维结构     

手性酞菁的合成及其绝对构型

在锂存在的条件下在正戊醇中回流环化四聚相应的光学活性的前驱体联二萘[2,1-e:1',2'-g][1,4]二羟基-5,6-邻苯二氰, 然后用醋酸酸化处理, 合成了一对对映的四个联二萘酚基团取代的手性自由酞菁四(联二萘[1,2-e:1',2'-g]-1,4-二羟基)[2,3-b;2',3'-k;2',3'-t;2'',3''-c']酞菁(1), 并利用一系列的光谱学方法以及元素分析表征了这种新型的手性酞菁化合物. 单晶X衍射分析确定了两种对映体的绝对构型, 从而阐明了自由酞菁(1)的手性分配.     

Two New Coordination Polymers Assembled with a Functionalized Ligand：Syntheses and Crystal Structures

Two new transition-metal organic coordination polymers [M(mna)2](M = Cd(1),Zn(2);mna = 2-mercaptonicotinic anion) have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction along with IR and elemental analyses.Compound 1 is generally a one-dimensional linear structure bridged through the sulfur donor of mna ligand,while 2 is a one-dimensional zigzag chain ligated via the oxygen donor of mna ligand.These compounds further result in three-dimensional structures via intermolecular π...π stacking interactions and/or hydrogen bonding interactions.The two compounds were structurally determined by single-crystal X-ray diffraction.Complex 1 crystallizes in monoclinic space group P21/c with a = 3.730(3),b = 13.973(12),c = 12.380(11) ,β = 97.953(18)°,V = 639.0(10) 3,Z = 2,CdC12H8O4N2S2,Mr = 420.72,Dc = 2.187 g/cm3,F(000) = 412,Rint = 0.0252,T = 293(2) K,μ = 2.052 mm?1,the final R = 0.0269 and wR = 0.0586 for 1377 observed reflections with I > 2σ(I).Complex 2 belongs to monoclinic space group P21/c with a = 13.376(2),b = 12.8429(14),c = 7.4856(10) ,β = 96.190(10)°,V = 1278.5(3) 3,Z = 4,ZnC12H8O4N2S2,Mr = 373.69,Dc = 1.941 g/cm3,F(000) = 752,Rint = 0.0414,T = 293(2) K,μ = 2.264 mm?1,the final R = 0.0418 and wR = 0.0966 for 2396 observed reflections with I > 2σ(I).     

点籽晶法快速生长中等口径KDP单晶及其性能表征

本文使用德国MERCK公司生产的KDP原料和自行研制的晶体快速生长装置,采用"点籽晶"快速生长法成功生长出了150 mm级中等口径的KDP单晶,晶体生长速度达到20 mm/d.晶体生长过程中,生长溶液稳定,没有杂晶出现,生长的晶体完好且透明.X射线粉末衍射和摇摆曲线分析表明晶体有着较好的结构完整性;同时,测试了晶体的透过光谱和光损伤阈值,发现快速生长的晶体有着较好的光学性能.