233 resultados para TPD


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本论文设计与合成出苯胺基元数分别为1,2,3,4,具有固定共轭长度和规整结构的新型氮硫共轭聚合物(PPSA;PPSAA;PPSTRA和PPSTEA),且聚合物在常见有机溶剂(THF,DMF和DMSO等)中具有良好的溶解性。随着苯胺基元的增加,其导电和掺杂特性逐渐接近于聚苯胺。含有苯胺四聚体的聚合物PPSTEA的光谱特性几乎与聚苯胺相同。PPSTEA有着良好的电化学可逆性和稳定性。只有当重复单元含有四个以上的苯胺基元(一个苯二胺基元和一个醌亚胺基元)时,才能进行质子酸掺杂,获得高电导率材料。与普通聚茉胺相同,含有四个苯胺基元的PPSTEA存在全还原态,中间氧化态和全氧化态,且三者之间可以进行相互转化。全还原态PPSTEA可进行碘氧化掺杂,其电导率约为10~(-2) S/cm。中间氧化态PPSTEA可进行质子酸掺杂,其盐酸掺杂后电导率可达10~0 S/cm。设计与合成出系列含有苯胺同系物的氮硫交替共轭聚全物,考察了亚砜 /质子酸体系变量参数对聚合反应的影响。位于苯环上的取代基为吸电子基团时,不利于聚合反应发生,所得聚合物分子量较低。取代基为推电子基团时,基本上不影响聚合反应的发生,所得聚合物的分子量与无取代基的PPSA相当。与此同时,合成了两种新型的超支化氮硫交替共轭聚合物。设计与合成出系列烷基和芳基取代的主分子量结构规整的氮硫交替共轭聚合物(PPSAR和PPSAOR),聚合物可溶于常见的有机溶剂且具有良好的成膜性。研究表明,这些聚合物均为富电性材料。PPSAR和PPSAOR都有着良好的空穴传输性能,代替有机空穴传输材料可大大改善其器件的综合性能。通过引入双键和苯硫醚基团对芳香二胺(TPD)分子进行结构修饰,成功地获得了系列高玻璃化转变温度(Tg)的新型空穴传输材料,所得系列TPD衍生物具有良好的空穴传输性能。同时还合成出了以三苯胺为核的Dendrimer有机化合物,发现其具有热稳定性好、三芳胺密度高和难以结晶等特点,可能成为一类具有潜在发展前途的有机空穴传输材料。

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本文以调控发光颜色、提高发光效率为目的,通过改变配体、中心金属离子、取代基等进行颜色调节;通过引入电子或空穴传输单元,实现发光分子的功能化进而改善载流子传输提高发光效率。文中主要以有机小分子和金属配合物为研究对象,它们本身都具有良好的发光性质。工作集中围绕以下几个问题展开:1、PPV齐聚物是一类高效发光的分子体系,如果在其中嵌入8一取代的哇琳单元对发光会有什么影响?2、使用含噁二唑(具有电子传输功能)的配体得到的金属配合物是否能同时拥有双重功能,即高效发光(金属配合物的特点)和优良的电子传输?3、由N2O-双齿配体转变成N,N-双齿配体,配合物的发光又会如何?4、稀土配合物具有高的光致发光效率,但电致发光效率非常低,能否通过咔哇或呛二吟功能化来改善载流子传输,提高电致发光效率?主要工作及取得的结果概述如下:1、经由Knoevenagel缩合反应合成了一系列共骊的2,21-(1,4-芳二乙烯基)双-8-取代喹啉。单晶X-射线衍射研究表明固态下存在分子间,π…π堆积相互作用,这对于载流子传输是比较有利的。喹啉8-位于的取代基的变化对发光影响不大,表明刚性共扼骨架对发光起主要贡献。改变中心的芳核,明显可以调控发光颜色。当存在分子内电荷转移时,与不存在的相比,发光显著红移。电致发光性质表明这些含双喳琳的PPV齐聚物是良好的发光和电子传输材料。2、存在分子内氢键的化合物2-(2-羟基苯基)-5-苯基-1,3,4-噁二唑(HOXD),具有激发态分子内质子转移(ESIPT)特性。在室温下,用365脚的紫外灯照射时表现强的兰色荧光。室温和低温(77K)下的磷光光谱表明它在固态下具有较强的磷光发射,与理论预测完全一致。多层电致发光器件ITO加PB/HOXD/BCP/Alq3/Mg:Ag最大亮度达到656cd/m2,电流效率为0.37cd/A。当把HoxD掺在cBP中时,亮度和效率都有一定程度的提高,达到870cd/m2和0.82cd/A。3、合成了含有德二哩配体(HOXD)的碱金属配合物MOxD(M=Li,Na,K)。我们发现配合物的发光颜色取决于中心金属离子,LiOXD是一个优良的蓝光材料,半峰宽是65nm,发射峰位在478nm,它也可以作为界面材料使用,起到和LIF相同的作用,即改善电子注入。同时作者首次报道了钠和钾的配合物可以用作发光材料。电致发光性质表明这些配合物是优良的蓝/绿色发光和电子注入/传输材料。4、使用从N双齿配体代替N,O-双齿配体(比如8-羟基喹啉),合成了含有2-(2-羟基喹啉)苯并咪唑的锌、铍和硼配合物。用硼配合物作为发光层的三层器件ITO/NPB/boron-complex/Alq3/LiF/A1所得到的光谱覆盖了从400到750nm的区域,表明获得了一个很好的白色发光。白光分别源于激子和激基复合物发光,由三种成分构成:来自于硼配合物的兰色发光(490nm);来自于Alq3的发光(535nln);NPB和BPh2(Pybm)界面形成的激基复合物发光(610nm)。器件最大亮度是110cd/m2最大效率是0.8cd/A。5、设计、合成了咔唑、噁二唑功能化的稀土馆配合物,期望通过改善空穴和电子传输来提高发光效率。含咔哇的配合物的双层器件发光光谱较宽,包括三价铺的特征发射和一个宽峰,可能是咔唑的发光。当使用TPD做空穴传输层时,噁二唑铺配合物的电致发光器件得到纯正明亮的红色发光,器件结构为ITO/TPD(40nm)/(OXD-PyBM)Eu(DBM)3(SOnm)/LiF(Inm)/Al(200m),启动电压为7.8V,在21v时达到最大亮度322cd/m2。亮度为57cd/m2和13.sv时电流效率最大,为1.9cd/A,对应外量子效率是1.7%。高的效率表明通过引入噁二唑基团,配合物的电子传输能力得到明显改善。6、初步研究了三线态发光的铱的金属有机配合物,得到了高亮度、高效率的绿色发光;对8-羟基喹啉锌配合物的高分子化也做了初步探讨。

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高分子发光材料除应具有优良发光性能外,还需具有优良电子传输性能和空穴传输性能。本论文以此为出发点,将具有优良空穴传输性能的芳胺类化合物和具有优良电子传输性能的噁二唑类化合物,通过无规共聚合调控发光基元和两类传输基元的含量,合成了系列的传输与发光一体化的即V类高分子发光材料,并探讨了聚合物本身的基本特性。同时,设计和制备了相应的单层结构器件和掺杂器件,考察了器件的器件性能。本论文主要工作内容及结果如下:1、成功的利用三类王芳胺类双醛:4,4'-二醛基-(4-辛氧基-苯基)-二苯胺(TPA双醛)、N,N'-二(4-辛氧基一苯基)-N,N'-二(4-甲醛基-苯基)-1,4-苯二胺(PDA双醛)和N,N,-二(4-辛氧基-苯基)-N,N,-二(4-甲醛基-苯基)-4,4' 联苯二胺(TPD双醛)和wittig麟盐无规共聚,得到三个系列双极传输高分子发光材料。2、聚合物主链中同时引入三芳胺类空穴传输基团和噁二唑电子传输基团,提高了器件性能。在TPA系列中,同时含有三芳胺和噁二唑全基团的聚合物比仅含有三芳胺基团聚合物的单层器件亮度及效率分别提高29和22倍,同时使器件的启动电压从9.3V下降到2.7V。在同样比较的情况下,在PDA系列中,聚合物的器件亮度及效率要提高近8倍,同时使器件的启动电压从5.3V下降到4.5V。在TPD系列中,聚合物的器件亮度及效率要提高44和38倍,同时使器件的启动电压从7.5V下降到5.7V。3、含有噁二唑基团聚合物分子的这种D-A体系所具有的分子内电荷转移性质,导致其荧光光谱和电致发光光谱红移。其中,TPA系列和TPD系列的电致发光光谱从绿光红移到了黄绿光,而PDA系列聚合物的电致发光光谱从黄绿光红移到了橙光。4、刚性的噁二唑基团的引入提高了聚合物的热稳定性,T以系列聚合物、PDA系列聚合物和TPD系列聚合物中含有噁二唑基团的聚合物的玻璃化转变温度在112-229℃之间,其热分解温度超过420℃。5、此三个系列聚合物中同时含有空穴和电子传输基元的双极分子溶液的紫外一可见吸收光谱和荧光光谱都有明显的溶剂化效应,表现出较强的分子内电荷转移特性。6、利用TPA系列聚合物中性能最好的聚合物TPA-OXD-PV1的良好电子和空穴传输性质,构造的单层掺杂器件,实现了橙色和红色发光。

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在本工作中,制备了一系列催化剂样品,其中有K、Ni、Mo单组份催化剂,K-Ni、K-Mo、Ni-Mo双组份催化剂及不同活性组份含量的K-Ni-Mo三组份催化剂。针对水煤气变换反应,对上述催化剂进行反应活性考察,得出如下结果:①催化剂各活性组份的最佳含量大致是NiO(3%), MoO_3(13%), K_2CO_3(6%);②催化剂制备中的最佳焙烧温度在400 ℃左右;③催化剂使用前用H_2S/H_2的混和气进行预处理其效果最佳;④催化剂的催化活性与催化剂表面硫的含量有关,当催化剂表面处于严重缺硫状态时其活性下降;⑤反应的最佳汽:气 = 0.5-1.5;⑥加压有利于催化剂活性的提高,在加压情况下催化剂的活性随着反应温度的增加通过一极大值(在约200 ℃左右),不加压的反应催化剂活性随着反应温度的提高而增加。在催化剂的表征部分,利用XPS、XRD、紫外可见温反射光谱、SEM、ESR、比表面、TPR、酸度测定、TPD、TPS、TPS-TPR等实验对我们所制备的催化剂进行了研究。最后,我们用ESR和XRD实验技术研究了MoO_3、M_2CO_3 (M = Li、Na、K、Cs)-MoO_3加热过程中的固相反应,知道MoO_3在空气中焙烧时可以失去晶格氧,使晶体中的一些Mo~(6+)变成Mo~(5+)。在焙烧过程中,Li、Cs~+的加入将阻止MoO_3晶格氧向气相氧的转变,对Mo~(5+)的生成有抑制作用。加入一定量Na~+、K~+的MoO_3在焙烧过程中,其晶格氧被活化更易失去它们对Mo~(5+)的生成有促进作用,这种作用的大小是Na~+ > K~+。

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本论文的工作就是寻找合适的催化剂,对丙烷脱氢进行氧化脱氢。目的是降低反应温度,提高产物的收率,探讨丙烷氧化脱氢的活性与催化剂表面性能的关系。一、丙烷在Cr-Al-O体系的催化剂上反应性能的研究。Cr_2O_3/Al_2O_3催化剂对丙烷脱氢具有较高的活性,在Cr_2O_3/Al_2O_3中加入稀土元素 La、Ce、Pr、Nd,发现催化剂的活性增加,其中掺Ce的催化剂活性最高,但反应产物的选择性最低。从SEM照片看出,稀土元素的加入,改变了催化剂的表面结构,使得表面孔隙增多,反应的转化率增大。在Cr_2O_3/Al_2O_3中加入V元素,发现催化剂的活性增加。由于Cr~(3+)V~(5+)O~(2-)→Cr~(3+)V~(4+)O~-→Cr~(2+)V~(5+)O~-;可以产生O~-,所以使C_3~0变成C_3H_7,和OH~-变得容易,使得反应的转化率增加。从TPD的结果看,掺V后,最大吸附峰的Tm增高,吸附峰中可能包含O_2~-和O~,高温吸附O~-增多,结果使反应的转化率增大,另一方面,O_2~-减少,由于O_2~-可能使C_3~-进一步氧化成完全氧化产物,结果产物的选择性增大。二、丙烷在Mo-Al-O体系的催化剂上氧化脱氢。MoO_3/Al_2O_3对C_3~0氧化脱氢具有较好的活性,在MoO_3/Al_2O_3中分别加入V和Fe, 从XRD结果可知,MoO_3/Al_2O_3中,当MoO_3wt%增加时,MoO_3、Al_2(MoO_4)_3的含量增加,催化剂活性增加,

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利用SiH_4和GeH_4作为源气体,对UHV/CVD生长Si_(1-x)Ge_x/Si外延层的表面反应机理进行了研究,通过TPD、RHEED等实验观察了Si(100)表面SiH_4的饱和吸附、热脱附过程,得出SiH_4的分解应该是每个SiH_4分子的4个H原子全部都吸附到了Si表面,SiH_4的吸附率正比于表面空位的4次方,并分析了GeH_4的表面吸附机制。在此基础上建立了UHV/CVD生长Si_(1-x)Ge_x/Si的表面反应动力学模型,利用模型对实验结果进行了模拟,二者符合得很好。

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简要介绍一种新的输入信号时序鉴别方法与电路。该电路的主要功能是对输入信号的时序进行鉴别和分拣,它可以鉴别出一个输入信号串中包含的各个脉冲的序号,并且产生与各个序号相对应的输出信号。可以鉴别的输人信号的序号为N=1,2,3,…,8。适用于多路时间幅度转换器(TAC)和多路时间数字转换器(TDC)系统,其输出信号可作TAC和TDC的停止信号。该电路输出信号的前沿tr≤3.2ns,传输延迟tpd≤20ns.

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A study of cooled Au-197 projectile-fragmentation products has been performed with a storage ring. This has enabled metastable nuclear excitations with energies up to 3 MeV, and half-lives extending to minutes or longer, to be identified in the neutron-rich nuclides Hf-183,Hf-184,Hf-186 and Ta-186,Ta-187. The results support the prediction of a strongly favored isomer region near neutron number 116.

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A comparative study on the annealing of the ITO substrates and the organic layers were conducted on Organic light-emitting device (OLED). We fabricated four devices with the structure of Al/Alq(3)/TPD: PVK/NiO/ITO/Glass, and investigated the effect of heat on device performance by selectively annealing. When the TPD: PVK layers were annealed at 90 degrees C with 30 min annealing time and the ITO substrates were annealed at 300 degrees C with a constant annealing time (100 min). We find the OLED shows obvious performance improvement in brightness and current efficiency, which is attributable to the fact that annealing reduces defects and improves the interface structures of the organics and the organic/ITO interfaces. On the other hand, an appropriate annealing would slow the transportation of the hole, thus finally leads to more balanced electron and hole.

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In this work, the structural and surface properties of Co-loaded sulfated zirconia (SZ) catalysts were studied by X-ray diffraction (XRD), N-2 adsorption, NH3-TPD, FT-IR spectroscopy, H-2-TPR, UV-vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and NO-TPD. NH3-TPD and FT-IR spectra results of the catalysts showed that the sulfation process of the support resulted in the generation of strong Bronsted and Lewis acid sites, which is essential for the SCR of NO with methane. On the other hand, the N-2 adsorption, H-2-TPR, UV/vis DRS, and XPS of the catalysts demonstrated that the presence of the SO42- species promoted the dispersion of the Co species and prevented the formation Of Co3O4. Such an increased dispersion of Co species suppressed the combustion reaction of CH4 by O-2 and increased the selectivity toward NO reduction. The NO-TPD proved that the loading of Co increased the adsorption of NO over SZ catalysts, which is another reason for the promoting effect of Co. (C) 2004 Elsevier Inc. All rights reserved.

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The catalytic performances of ZrO2-based catalysts were evaluated for the synthesis of higher alcohols from synthesis gas. The crystal phase structures were characterized by X-ray diffraction (XRD) and UV Raman. The results indicated that ZrO2 and Pd modified ZrO2 catalysts were effective catalysts in the synthesis of ethanol or isobutanol, and their selectivities basically depended on the crystal phase of ZrO2 surface. The ZrO2 with surface tetragonal crystal phase exhibited a high activity to form ethanol, while the ZrO2 with surface monoclinic crystal phase exhibited a high activity to form isobutanol. Temperature-programmed desorption (TPD) experiment indicated that the high activity of isobutanol formation from synthesis gas over monoclinic zirconia was due probably to the strong Lewis acidity of Zr4+ cations and the strong Lewis basicity of O2- anions of coordinative unsaturated Zr4+-O2- pairs on the surface of monoclinic ZrO2. (C) 2003 Elsevier B.V. All rights reserved.

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Acid strength distribution and the distribution of aromatics formed in the FCC gasoline conversion reaction on a ZSM-5 zeolite with different Na contents have been studied. With increasing Na content in the ZSM-5 zeolite, the acid sites determined by NH3-TPD technique, especially the strong acid sites, clearly decrease. When used as catalyst for the aromatization reaction, the transformation of olefins in the FCC gasoline into aromatics is governed directly by the strong acid sites on the ZSM-5 catalyst. Only under the conditions that a ZSM-5 catalyst possesses suitable strong acid sites is reaction temperature favorable for the aromatics formed.

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ZSM-5 zeolites with similar SUM ratio were synthesized successfully using various templates (n-butylamine (BTA), ethylamine (ETA), isopropylamine (IPA), ethylenediamine (EDA), ethanol (ETL), ethanol-ammonium (ETL-AM) and no template (NT)) under hydrothermal conditions. The samples were characterized by XRD, SEM, XRF, NH3-TPD and BET surface area measurements in order to understand the template effects and the differences of the ZSM-5 samples. The synthesis of ZSM-5 with organic templates was relatively easier than those with inorganic templates and without template. SEM results revealed that ZSM-5 synthesized with different templates had different morphology and particle size. The Si/Al ratio and BET specific surface area of the sample with ethanol as template was the lowest. NH3-TPD results showed that the sample synthesized without template had fewer strong acid sites than others. n-Hexane cracking reaction was carried out over the samples to evaluate the catalytic properties. All ZSM-5 zeolites were effective in n-hexane cracking reaction, especially for the sample synthesized without template. (C) 2004 Elsevier B.V. All rights reserved.

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Three types of metal-containing molecular sieves with AFI, AEL and CHA structures (Me = Co, Mn, Cr and V) were synthesized hydrothermally and characterized by XRD, XRF, TG, TPR, NH3-TPD and FT-IR. It was revealed that metals were incorporated into the framework of molecular sieves and induced the presence of charge centers. Both cobalt and manganese in the framework of AIPO-5, AlPO-11 and SAPO-34 were not reducible before the structure collapse. The redox behaviours of these catalysts in cyclohexane oxidation at 403 K using O-2 as oxidant were examined. CoAPO-11 exhibited best activity and good selectivities for the monofunctional oxidation products (88.5%). Cyclohexanol was the major product over most catalysts, whereas for Cr-containing molecular sieves, high selectivity of cyclohexanone was observed. Investigation of reaction mechanism based on CoAPO-11 and CrAPO-5 catalysts indicated that the decomposition of cyclohexyl hydroperoxide (CHHP), the intermediate in cyclohexane oxidation, followed the pathway: cyclohexanone <-- CHHP --> cyclohexanol -->cyclohexanone. (C) 2004 Elsevier B.V. All rights reserved.