双组分茂金属催化剂催化乙烯聚合的研究

选择能形成支链的不对称桥联茂金属化合物Me2 C[(Cp) (Ind) ]ZrCl2 和非桥联的不同结构的茂金属化合物二氯二 (烯基取代环戊二烯 )锆如 ( Cp) 2 ZrCl2 ,(Cp) 2 ZrCl2 和 (Cp) 2 ZrCl2 ,以MAO为助催化剂 ,分别组成三组双组分茂金属催化剂的催化体系 ,催化乙烯聚合 .结果表明 ,两类催化剂组成的双组分茂金属催化体系催化乙烯聚合能得到支化的宽分子量分布的聚乙烯 ;聚合温度和改变两种茂金属催化剂的摩尔比对催化活性和分子量有很大影响 .因此可以利用改变双组分茂金属催化剂的摩尔比例和聚合温度来调控聚合物的分子量和分子量分布 .改变两种茂金属催化剂的摩尔比和聚合温度也能使聚合物的结晶度发生改变     

乙丙嵌段共聚物的X-射线衍射研究

用大角X-射线衍射(WAXD)方法对按嵌段聚合程序合成的聚丙烯(PP)和乙丙共聚物(EPR)的嵌段共聚物PP-EPR和PP-EPR-PP,以及相应的混合物进行对比研究.乙丙共聚物及其共混物均发现在2θ=20°处存在由EPR中PP链段引起的γ-晶型衍射峰.通过诠释X-射线衍射图,计算结晶度,微晶尺寸和晶格参数等表明,用δ-TiCl_3-Et_2AlCl催化剂获得了嵌段共聚物结构.     

CeO2对甲醇裂解用Cu-Ir双金属催化剂的影响

用甲醇裂解模型反应,程序升温(TPR,TPD)和XRD等技术研究了CeO2促进的Culr双金属催化剂.结果表明适量CeO2的加入可以改善催化剂的表面性质,提高催化剂的活性、选择性和稳定性.XRD表征发现铜铱双金属催化剂主要是以Cu19Ir和少量的Cu2O形式存在于催化剂中,Cu19Ir是催化剂的主要活性组份,且CeO2的加入提高了催化剂活性组份的分散度.结合TPR表征结果,发现CeO2的加入有利于活性物种Cu2O的形成,一定量Cu+的存在有利于H2和CO选择性的提高.     

星形和树枝状二茂铁基聚合物

介绍近年来星形和树枝状聚藏金属主要是含二藏铁基的星形和树枝状材料的研究进展。     

Improved Voltage and Fill Factor by Using Zinc Oxide Thin Film as a Barrier Layer in Dye-Sensitized Solar Cells

A series of dye-sensitized solar cells based on ZnO-modified TiO2 nano-porous films have been prepared. The current-voltage characteristics of the cells show that the ZnO-modification can improve the open-circuit voltage and the fill factor but can decrease the short-circuit current. Dark current and transient photovoltage measurements are used to study the back reaction. It is indicated that the recombination process is suppressed by blocking the hole transporting from the nano-porous TiO2 since the surface of the semiconductor is almost fully covered with ZnO as a barrier layer.     

相位测量轮廓术中随机相移误差的校正算法

在相位测量轮廓术(PMP)中．随机相移误差足导致测量误差的重要因素,提出一种新的随机相移误差的校正算法,在五步相移的基础上不需要求解相位分布．通过近似处理可以直接求解相移过程中存在的随机相移误差,在保证精度的情况下,能大大减少迭代次数和计算量。推导了新算法的计算公式,详细说明了随机相移误差的求解过程。计算机模拟和实验证实了新的算法的有效性。与In-bok Kong的算法相比较,新算法能大大减少迭代次数和计算量。该新算法也同样适用于相移干涉计量。     

Segregation behavior of magnetic ions in continuous flowing solution under gradient magnetic field

The research of magnetic separation starts from magnetic solid particles to nanoparticles, and in the research progress,particles become smaller gradually with the development of application of magnetic separation technology. Nevertheless,little experimental study of magnetic separation of molecules and ions under continuous flowing conditions has been reported. In this work, we designed a magnetic device and a "layered" flow channel to study the magnetic separation at the ionic level in continuous flowing solution. A segregation model was built to discuss the segregation behavior as well as the factors that may affect the separation. The magnetic force was proved to be the driving force which plays an indispensable role leading to the segregation and separation. The flow velocity has an effect on the segregation behavior of magnetic ions,which determines the separation result. On the other hand, the optimum flow velocity which makes maximum separation is related to the initial concentration of solution.     

Thermoelectric properties of lower concentration K-doped Ca_3Co_4O_9 ceramics

The tuning of electron and phonon by ion doping is an effective method of improving the performances of thermoelectric materials. A series of lower concentration K-doped Ca_(3-x)K_xCo_4O_9(x = 0, 0.05, 0.10, 0.15) polycrystalline ceramic samples are prepared by combining citrate acid sol-gel method with cold-pressing sintering method. The single-phase compositions and plate-like grain morphologies of all samples are confirmed by x-ray diffraction and field emission scanning electron microscope. The effects of lower concentration K doping on the thermoelectric properties of the material are evaluated systematically at high temperatures(300–1026 K). Low concentration K doping causes electrical conductivity to increase up to 23% with little effect on the Seebeck coefficient. Simultaneously, the thermal conductivity of K-doped sample is lower than that of the undoped sample, and the total thermal conductivity reaches a minimum value of approximately1.30 W·m~(-1)·K~(-1), which may be suppressed mainly by the phonon thermal conduction confinement. The dimensionless figure-of-merit ZT of Ca_(2.95)K_(0.05)Co_4O_9 is close to 0.22 at 1026 K, representing an improvement of about 36% compared with that of Ca_3Co_4O_9, suggesting that lower concentration K-doped Ca_3Co_4O_9 series materials are promising thermoelectric oxides for high-temperature applications.     

Air Stability of Cs2CO3:Ag/Ag Cathode for Organic Light-Emitting Diodes

We report the superior stability of the composite Cs2CO3 ：Ag/Ag cathode structure, which can be used in efficient organic light-emitting diodes （OLEDs）. Devices with the Cs2CO3：Ag （1：10, 5nm）/Ag （95nm） cathode show a considerably improved lifetime compared with the control device with the Cs2CO3 （0.5 nm）/Ag （100 nm） cathode. The composite Cs2CO3 ：Ag/Ag film is proved to be stable in the atmosphere. X-ray diffraction （XRD） is applied to analyze the crystalline structure of the Cs2CO3：Ag film, and it is demonstrated that CsAg alloy is formed, leading to the improved stability of the thin film and the devices.     

ZnO外延膜与蓝宝石衬底的取向偏差及其弯曲变形

采用常压MOCVD方法在Al2O3(00．1)衬底上生长出了高质量ZnO单晶薄膜。由ZnO(00．2)面和Al2O3(00．6)面及ZnO(10．2)面和Al2O3(11．6)面X射线双晶(w／2θ衍射曲线的相对峰位,得到ZnO外延膜的晶格常数及外延层和衬底间的取向差异角。结果表明外延层和衬底在应力作用下产生了取向差和晶格畸变,并且取向倾斜方向与衬底的切割倾角方向一致;高温直接生长的样品的取向差比有低温缓冲层样品更大,晶格畸变也更严重。高温直接生长的样品弯曲半径小而应力更大;实验测量的应力值和理论计算的热应力值之间存在差异,原因主要是晶格失配应力的存在。有缓冲层的样品由于能更好地弛豫晶格失配引入的应力,热应力所占整个残余应力的比例相对更大。