NiP非晶态合金的负载方法及催化剂的结构与催化性能

采用ＮｉＢ作为引导剂,使ＮｉＰ完全定向沉积到载体上,用ＩＣＰ,ＸＲＤ,ＤＳＣ,ＢＥＴ,ＴＥＭ对制备的负载型ＮｉＰ（Ｂ）催化剂进行表征,研究了这类催化剂对乙烯中微量乙炔的选择加氢性能,结果表明,ＮｉＰ（Ｂ）以超细颗粒分散到载体上,由于少量Ｂ的存在,使其比相应的ＮｉＰ或ＮｉＢ具有更高的热稳定性。非晶态ＮｉＰ（Ｂ）合金催化剂具有比相应的晶态合金更好的催化性能。低温氢气处理可以除去表面镍的氧化物,从而提高     

Ni-Sn电极析氢性能研究

在Fe基底材料上电镀Ni_Sn合金制备低析氢过电位的阴极活性材料 .该材料适用于氯碱工业隔膜型电解槽 ,可达到降低槽压、节能降耗的目的 .在电解槽阴极溶液NaOH 12 0 g/L ,NaCl190 g/L ;温度 90℃ ,阴极极化电流密度i=15 0mA/cm2 的条件下 ,测得其析氢过电位为 88mV .X射线衍射分析表明 ,该种材料与传统装饰用Ni_Sn合金的结构状态有所不同 .采用循环伏安法对Fe电极和Ni_Sn合金电极进行分析 ,可初步判断Ni_Sn合金对氢的吸附较弱 ,有利于析氢反应的进行     

ICP-AES测定钕铁硼永磁合金中主量元素

采用ICP-AES同时测定了钕铁硼永磁合金中的Nd、Fe、Co、B、Zr5种主量元素.选择了合适的分析线和样品测定浓度,确定了各元素的检出限为0.54-1.94μg/L,加标回收率为90.5%-119%.方法准确,快速、简便,用于生产实践中,结果令人满意.     

Adsorption of ethene on Pt(1 1 1) and ordered PtxSn/Pt(1 1 1) surface alloys: A comparative HREELS and DFT investigation

The adsorption of ethene (C₂H₄) on Pt(1 1 1) and the Pt₃Sn/Pt(1 1 1) and Pt₂Sn/Pt(1 1 1) surface alloys has been investigated experimentally by high-resolution electron energy loss spectroscopy and temperature programmed desorption. The experimental results have been compared with density functional theory (DFT) calculations allowing us to perform a complete assignment of all vibration modes and loss features to the species present on the surfaces. On Pt(1 1 1) as well as on the Pt-Sn surface alloys an η² di-σ-bonded conformation of ethene has been found to be the most stable adsorbed form. In addition to this majority species a minor amount of π-bonded ethene has been identified, which is more abundant on the Pt₂Sn surface alloy than on the other surfaces. Additionally the HREELS spectra of ethene on Pt(1 1 1) and the Pt-Sn surface alloys differ only slightly in terms of the energetic positions of the loss peaks.     

Electronic structure,magnetic properties,and microstructural analysis of thiol-functionalized Au nanoparticles: role of chemical and structural parameters in the ferromagnetic behaviour

The present work describes the field emission characteristics of nanocrystalline metal clusters decorated multi walled carbon nanotubes (MWNT) field emitters fabricated over flexible graphitized carbon cloth. MWNT have been synthesized by catalytic chemical vapour decomposition (CCVD) of acetylene over Rare Earth (RE) based AB₂ (DyNi₂) alloy hydride catalyst. Fine powders of RE based AB₂ alloy hydride catalysts have been prepared by hydrogen decrepitation technique. The as-grown carbon nanotubes (CNTs) are purified by acid and heat treatments and characterized using XRD, SEM and TEM. Purified MWNT have been decorated with nanocrystalline Pd, Pt and Pt–Ru metal clusters using a simple chemical reduction method. The characterization of metal decorated CNTs were done by using XRD, SEM, TEM, HRTEM and EDX. Nanocrystalline Pd, Pt and Pt–Ru metal clusters decorated MWNT field emitters have been fabricated over graphitized carbon fabric using spin coating method. The field emission characteristics have been studied using an indigenously fabricated set up and the results are discussed. The samples show excellent emission properties with a fairly stable emission current over a period of 4 h. As the presence of the graphitic layer provides strong adhesion between the nanotubes and carbon cloth, the use of graphitized carbon cloth as substrate opens new possibilities for CNT field emitters.     

Synthesis and Characterization of ZnO Bicrystalline Nanosheets Grown via Ag-Au Alloy Catalyst

ZnO bicrystalline nanosheets have been synthesized by using Ax=AU1-x alloy catalyst via the vapor transport and condensation method at 650 ℃. High resolution transmission electron microscopy characterization reveals a twin boundary with {01-13} plane existing in the bicrystalline. A series of control experiments show that both AgxAu1-x alloy catalyst and high supersaturation of Zn vapor are prerequisites for the formation of ZnO bicrystalline nanosheet. Moreover, it is found that the density of ZnO bicrytalline nanosheets can be tuned through varying the ratio of Ag to Au in the alloy catalyst. The result demonstrates that new complicated nanostructures can be produced controllably with appropriate alloy catalyst.     

硅烷类外给电子体对丙烯-丁烯序贯聚合的调控作用

外给电子体(ED)作为负载型Ziegler-Natta催化剂的一个重要组分, 在影响α-烯烃的催化活性及聚合物的立构规整性方面发挥着重要作用. 本文研究了4种不同结构及电子密度的硅烷类外给电子体[二甲基二甲氧基硅烷(D1)、 二丁基二甲氧基硅烷(D2)、 二苯基二甲氧基硅烷(D3)及二环戊基二甲氧基硅烷(D4)]对丙烯均聚及丙烯(一段)-丁烯(二段)序贯聚合的影响. 结果表明, ED对烯烃聚合的催化活性、 活性中心数及活性中心定向能力都具有显著的影响. 密度泛函理论(DFT)模拟计算表明, 随着ED的空间位阻和电子密度增加, ED在MgCl₂表面的吸附能降低, 吸附稳定性降低; ED的空间位阻和电子密度增加有利于提高丙烯聚合活性中心的定向能力, 当n(D4)/n(Ti)=20时, 合成的聚丙烯(PP)中的等规聚丙烯(iPP)组分含量达到92.8%. 当n(ED)/n(Ti)=15时, 丙烯聚合的聚合速率常数达到最大值; 具有更大空间位阻和电子密度的ED使得丙烯-丁烯序贯聚合的活性中心具有更强的定向能力, ED对丁烯(二段)聚合活性及聚丙烯/聚丁烯合金（PBA）中等规聚丁烯(iPB)组分的熔点影响更显著.     

Ni deposition on the pentagonal surface of an icosahedral Al-Pd-Mn quasicrystal

We have evaporated Ni on the pentagonal surface of an icosahedral Al-Pd-Mn quasicrystal kept at room temperature. At the initial stage of growth, Ni intermixes with the substrate surface. Subsequently, Al from the quasicrystal matrix migrates to growing layers. The modified chemical composition in an initially icosahedral region near the surface induces a structural transformation. An Al-Pd-Mn alloy is formed which consists of five cubic domains with dimensions in the nm-range exposing their (1 1 0) faces parallel to the surface. These domains are azimuthally rotated by 2π/5 with respect to each other and aligned with symmetry directions of the icosahedral substrate. Al-Mn-Ni, Al-Ni, and Ni overlayers adopt both structure and orientation of these domains which stabilises Ni in a novel body-centred cubic phase. Ni-rich overlayers exhibit out-of-plane magnetic ordering.     

直读光谱法应用于金属合金分析与电镀层厚度测定之间的区别

本文从光谱分析原理比较入手，分析了利用火花原子发射光谱仪（直读光谱仪）进行金属合金分析和金属电镀层厚度测定之间的一系列区别，为火花原子发射光谱分析指出了一个崭新的应用领域。     

铝合金中十种微量元素的光谱分析

本文叙述的方法是将固体铝合金样品在车床或铣床上加工成平面，然后以选好的仪器测量条件，用铝元素做内标，按照自编分析程序在ＭＢＳ火花台上氩气气氛中激发，进行火花－原子发射光谱法测定。此方法快速、简便，标准样品所得分析结果基本与标称值吻合，３次测定结果相对偏差≤２０％。在重复性实验中，不同时间内测定同一样品１０次，１０个被测元素结果的相对标准偏差ＲＳＤ≤１０％。