Simulating the Dynamics of Bimetallic Clusters Deposited onto a Surface Using Molecular Dynamics

This paper examines the interface development between a single crystalline Ag matrix and core-shell AgnCom nanoclusters that have been deposited with energies varying between 0.25 eV and 1.5 eV per atom using computer modeling techniques. Clusters undergo deformation as a result of the slowing down;they may also become epitaxial with the substrate and maintain their core-shell structure. A detailed analysis of the effects of the cluster-surface interaction is conducted over a realistic size and energy range, and a model is created to show how clusters accumulate. It is discovered that both the silver shells and the cobalt cluster cores exhibit limited epitaxy with the substrate, and that the contact produced is only a few atomic layers thick. The effect is higher for Ag shells than for Co cores, and it is not very energy dependent.

Synergistic integration of metallic Bi and defects on BiOI: Enhanced photocatalytic NO removal and conversion pathway

Surface plasmon resonance(SPR)of metals may provide a way to improve light absorption and utilization of semiconductors,achieving better solar light conversion and photocatalysis efficiency.This study uses the advantages of SPR in metallic Bi and artificial defects to cooperatively enhance the photocatalytic performance of BiOI.The catalysts were prepared by partial reduction of BiOI to form Bi@defective BiOI,which showed highly enhanced visible photocatalytic activity for NOx removal.The effects of reductant quantity on the photocatalytic performance of Bi@defective BiOI were investigated.The as-prepared photocatalyst(Bi/BiOI-2)using 2 mmol of reductant NaBH4 showed the most efficient visible light photocatalytic activity.This enhanced activity can be ascribed to the synergistic effects of metallic Bi and oxygen vacancies.The electrons from the valence band tend to accumulate at vacancy states;therefore,the increased charge density would cause the adsorbed oxygen to transform more easily into superoxide radicals and,further,into hydroxyl radicals.These radicals are the main active species that oxidize NO into final products.The SPR effect of elemental Bi enables the improvement of visible light absorption efficiency and the promotion of charge carrier separation,which are crucial factors in boosting photocatalysis.NO adsorption and reaction processes on Bi/BiOI-2 were dynamically monitored by in situ infrared spectroscopy(FT-IR).The Bi/BiOI photocatalysis mechanism co-mediated by elemental Bi and oxygen vacancies was proposed based on the analysis of intermediate products and DFT calculations.This present work could provide new insights into the design of high-performance photocatalysts and understanding of the photocatalysis reaction mechanism for air-purification applications.

Cu-Co bi-metal catalyst prepared by perovskite CuO/LaCoO_3 used for higher alcohol synthesis from syngas

Cu-Co bi-metal catalysts derived from CuO/LaCoO3 perovskite structure were prepared by one-step citrate complexing method, and the structure evolution reaction from CuO/LaCoO3 to Cu-Co2C/La202CO3 under 1-12 pretreatment was investigated by techniques of XRD, TPR and TEM. The results suggest that a much higher dispersion of copper significantly enhanced the reduction of cobalt, and a stronger interaction between copper and cobalt ions in LaCoO3 particles led to the formation of bi-metallic Cu-Co particles in the reduced catalysts and the enrichment of Co on the surface of bimetallic particles. The prepared catalysts were highly active and selective for the alcohol synthesis from syngas due to the presence of copper-modified C02C species.

Bi-phasic Simulation of Metal Injection Moulding:Constitutive Determinations

To predict the segregation effect in metal injection moulding (MIM) injection, a bi-phasic model based on mixture theory is adopted in simulation. An explicit algorithm is developed and realized by the authors, which conducts the simulation to be a cost-effective tool in MIM technology. In case of the bi-phasic simulation, the viscosity behaviours are necessary to be determined for the flows of each phase while only the viscosity of mixture is measurable by tests. It is a crucial problem for application of the bi-phasic simulation of MIM injection. A reasonable method is hence analysed and proposed to determine the viscosity behaviours of each phase. Even though this method may be furthermore modified in the future, it results in the practical simulation of segregation effects with reasonable parameters. The simulation results are compared with the measurements on injected specimens.

An Exploratory Study of Tridentate Amine Extractants: Solvent Extraction and Coordination Chemistry of Base Metals with <i>Bis</i>((1<i>R</i>-benzimidazol-2-yl)methyl)amine

Solvent extraction of base metals using bis((1-decylbenzimidazol-2-yl)methyl)amine (BDNNN) showed a lack of pH-metric separation of the metals. The extraction system was described quantitatively using the equilibria involved to derive the mathematical explanation for the two linear log D vs pHe plots for each metal ion extraction curve, and coordination numbers could also be extracted from the two slopes. The lack of separation was attributed to the absence of stereochemical “tailor making” since the complexes isolated from the reaction of the ligand, bis((1H-benzimidazol- 2-yl)methyl)amine (NNN), with base metals suggested the formation of similar octahedral complex species from spectral and crystal structure evidence. The bis tridentate coordination observed was in agreement with information extracted from the extraction data. This investigation opens up an opportunity and an approach for the evaluation of amines as extractants but cautions against tridentate ligands.

Synthesis,Crystal Structure and Blue Photoluminescence of a Metal-organic Framework Constructed from Triangular [Zn_3(μ_3-OH)] Clusters with Bis(tetrazole)amine Ligands

A new metal-organic framework, {Zn[Zn3（BTA）3（μ3-OH）（H2O）3]2}n 1, has been synthesized under hydrothermal reaction of ZnCl2 and bis（5-tetrazolyl）amine （H2BTA）, and characterized by elemental analysis, FT-IR, Raman spectrum, X-ray single-crystal diffraction, TGA and photoluminescence measurements. Compound 1 crystallizes in the trigonal system, space group P-3cl, a = 13.667（3）, c = 12.981（3） A, V = 2099.6（8） A3 and Z = 2. The BTA2- ligand in 1 assumes theμ3 tetradentate mode with both 1,2- and 1,4-tetrazole bridges, generating an unusual 2-D layer, in which the [Zn3（μ3-OH）] triangular motifs act as three-connecting nodes and the mononuclear Zn atoms as six-connecting nodes that are inter-linked by organic ligands. Adjacent 2-D metal-organic layers are linked by strong hydrogen bonds to form a novel 3-D supramolecular framework. Complex 1 exhibits blue fluorescence emission in the solid state at ambient temperature.

Spectral, Thermal and Antibacterial Studies for Bivalent Metal Complexes of Oxalyl, Malonyl and Succinyl-bis-4-phenylthiosemicarbazide Ligands

The thermogravimetry (TG) and derivative thermogravimetry (DTG) have been used to study the thermal decomposition of some oxalyl (H4OxTSC), malonyl (H4MaTSC) and succinyl-bis-4-phenyl- thiosemicarbazide (H4SuTSC) ligands and their metal complexes using Horowitz-Metzger (HM) and Coats-Redfern methods. The kinetic thermodynamic parameters such as: E*, ΔH*, ΔS*and ΔG* are calculated from the DTG curves. The isolated complexes have the general composition [M2(L) (H2O)6], where M=Cu(II), Zn(II), L=MaTSC and M=Co(II), Cu(II) or Sn(II) and L=Su TSC and [M2(L) (H2O)n]·nH2O where M=Cu(II), Co(II) or Sn(II), L=OxTS or Ma TSC. The tested compounds show a good activity against four strains of bacteria Gram negative Escherichia coli, Pseudomonas aeruginosa species and gram-positive Bacillus cereus and Staphylococcus aureus.

Phase Behaviors in Bi-phase Simulation of Powder Segregation in Metal Injection Molding

Powder segregation induced by mold filling is an important phenomenon that affects the final quality of metal injection molding （MIM）. The prediction of segregation in MIM requires a bi-phase flow model to describe distinctly the flows of metallic powder and polymer binder. Viscous behaviors for the flows of each phase should hence be determined. The coefficient of interaction between the flows of two phases should also be evaluated. However, only viscosity of the mixed feedstock is measurable by capillary tests. Wall sticking is supposed in the traditional model for capillary tests, while the wall slip is important to be taken into account in MIM injection. Objective of the present paper is to introduce the slip effect in bi-phase simulation, and search the suitable way to determine the viscous behaviors for each phase with the consideration of wall slip in capillary tests. Analytical and numerical methods were proposed to realize such a specific purpose. The proposed method is based on the mass conservation between the capillary flows in mono-phase model for the mixed feedstock and in bi-phase model for the flows of two phases. Examples of the bi-phase simulation in MIM were realized with the software developed by research team. The results show evident segregation, which is valuable for improving the mould designs.

Doping dependent metal to insulator transition in the(Bi,Pb)-2212 system:The evolution of structural and electronic properties with europium substitution

The present work investigates the effect of europium substitution on the （Bi, Pb）-2212 system in the concentration range 0.5 ≤ x ≤1.0. Phase analysis and lattice parameter calculations on the powder diffraction data and the elemental analysis of EDX show that the Eu atoms are successfully substituted into the （Bi, Pb）-2212 system. Resistivity measurements （64-300 K） reveal that the system exhibits superconductivity at x ≤ 0.5 and semiconductivity at x 〉 0.5. With the complete suppression of superconductivity which is known to be a quasi-two dimensional phenomenon in these materials, a metal to insulator transition takes place at x = 0.6 and the predominant conduction mechanism is found to be variable range hopping between localized states, resulting in macroscopic semiconducting behaviour. The results of electrical and structural properties of the doped （Bi, Pb）-2212 compounds suggest that the decrease of charge carrier concentration and the induced structural disorder are the more effective and dominant mechanisms in the origin of the metal to insulator transition and suppression of superconductivity due to Eu substitution at its Sr site.

A Three-dimensional Porous Metal-organic Framework Based on Cyano Unit and 1,4-Bis(1,2,4-triazol-1-yl)butane(btb):{[Cu_8(btb)_2(CN)_8].3H_2O}_n

The title coordination polymer 1,{[Cu8（btb）2（CN）8].3H2O}n（btb = 1,4-bis（1,2,4-triazol-1-yl）butane）,has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction.Complex 1 crystallizes in monoclinic,space group C2/c with a = 1.2938（3）,b = 1.9422（5）,c = 0.9406（2） nm,β = 121.891（4）°,V = 2.0066（9） nm3,C24H30Cu8N20O3,Mr = 1155.00,Dc = 1.912 g/cm3,μ（MoKα） = 4.209 mm？1,F（000） = 1140,GOF = 1.184,Z = 2,the final R = 0.0634 and wR = 0.1503 for I 2σ（I）.In complex 1,one-dimensional CuCN zigzag chains are linked by triazolyl groups of btb ligands to form two-dimensional networks,which are further bridged by 1,4-butyl moieties of btb ligands to fabricate a three-dimensional order framework,in which one-dimensional ellipsoid-like channels are observed.

弯曲载荷下双金属机械复合管内衬层屈曲失效机理

双金属机械复合管是油气田集输管线防腐控制的主要措施之一,而内衬层的失效是制约复合管工程应用的关键难题。为研究双金属机械复合管内衬层屈曲失效机理,建立弯曲载荷下复合管力学模型,研究成型压力、工作内压及复合管结构参数对内衬层失效模式的影响规律。结果表明:增加成型后的残余接触压力有助于提高内衬层的抗屈曲能力;较高的工作内压能够延缓内衬层屈曲时间,减小其褶皱幅值;成型前复合管层间初始间隙减小有利于提高内衬层抗屈曲能力;随着外基管壁厚、内衬管壁厚、复合管内径的增加,内衬管的抗屈曲能力增强。

Dioxygen Affinities and Biomimetic Catalytic Oxidation Performance of Transition-metal Complexes with Unsymmetrical Bis-Schiff Bases

The oxygenation constants and thermodynamic parameter (ΔHo, ΔSo) of Co (II) complexes with unsymmetrical bis-Schiff baeses were measured and their Mn(III) complexes as models of mimicking monooxygenase were employed to catalyze epoxidation of styrene. The effect of substituent R in a salicylidene of ML1~ML4 [ M = Co (II), Mn (III)Cl ] on the dioxygen affinities and biomimetic catalytic oxidation performance were also investigated. Among them, the MnL4Cl containing a pendant benzoaza crown ether ring showed highest conversion and selectiviy up to 54.9% and 96.9% respectively.

三维多孔铜及表面修饰铋协同构筑无枝晶锂金属电极

以化学镀制备的具有微米级三维(3D)多孔结构的3D多孔铜为基底,在其表面电沉积铋修饰层,构建了3D Cu@Bi;将其作为锂金属电极集流体.孔径约5μm的3D多孔结构具有高表面积,有利于降低局部电流密度,电流密度分布更均匀,其大容纳空间可缓解体积变化和释放应力,抑制锂枝晶生长.Bi的亲锂性促进了界面动力学,降低了形核过电位,增强了锂沉积/剥离的可逆性.在3D多孔结构和铋修饰层的协同作用下,锂金属沉积容量>4 mA·h/cm^(2)时,电极表面仍保持平整、光滑;由其组装的半电池经过200次循环后,库仑效率(CE)可保持在98.5%以上;由其组装的对称电池在电流密度为0.5 mA/cm^(2),面容量为1 mA·h/cm^(2)时,可稳定循环1500 h以上,循环100次后电极表面仍光滑、无枝晶;以磷酸铁锂为正极组装的LFP||3D Cu@Bi@Li全电池在1.0C倍率下经过200次循环后,显示出132 mA·h/g的高容量和约87.2%的容量保持率.

添加Bi_2O_3对AgSnO_2触头物理及电接触性能的影响

以Bi_2O_3为添加剂,采用粉末冶金法制备不同掺杂量的Ag SnO_2触头材料试样。测量Ag对氧化物基片的润湿角,测试了试样的密度、电导率、接触电阻、燃弧能量等参数,分析了Bi_2O_3对Ag SnO_2触头材料润湿性的影响。结果表明,添加适量的Bi_2O_3对Ag SnO_2触头材料的物理和电接触性能有明显的改善,Bi_2O_3含量为1.5%时Ag SnO_2触头材料的整体性能达到最佳。润湿角随着Bi_2O_3含量增大呈现出波动增大的规律,与Ag SnO_2触头材料接触电阻、燃弧能量的变化规律基本吻合。

汉长安城武库出土铠甲片与铁铤的制作工艺研究

汉长安城武库遗址出土了大批西汉铁器,其中铠甲片、金属镞出土数量丰富,种类繁多。本文系统分析了24件铠甲片与17件残镞铁铤,发现残铁铤既包括铜镞之铤,也存在铁镞之铤,且存在不同的接铸顺序;所分析的铠甲片属于铜铁复合器,与铜镞之铤均存在超薄的夹铜层结构。依据两者微观结构特征,本文进一步认为具有铜铁复合架构的铠甲片是由这些铜镞之残铤经退火、锻打制成,且铠甲片的整个加工流程应完成于武库内,因此武库除屯藏兵备的职能外,还具有铁器锻造成型、加工的功能。

锡铋合金/肉豆蔻酸制备具有金属外壳的储能木材

【目的】利用锡铋合金对肉豆蔻酸浸渍材进行热处理,在热的驱动下将锡铋合金引入木材内部,以解决木基相变储能材料面临的液体泄漏和导热性差问题。【方法】以浸渍了肉蔻豆酸的杨木为基材,通过高低温交替热处理将锡铋合金与基材结合,制备具有金属外壳的储能木材。利用扫描电镜、邵氏硬度计、万能力学试验机、导热系数仪、差式扫描量热仪对储能木材的微观形貌、端面硬度、顺纹抗压强度和热性能进行测试。【结果】在160~220℃热处理1~5 min下试样质量增长效果显著,力学性能与热性能随着热处理温度的上升与时间的延长而提升,顺纹抗压强度和端面硬度相较于未处理材分别提升了120.02%~149.59%、13.53%~46.93%,轴向、径向导热率分别提升了34.18%~165.67%、38.11%~80.70%。在190℃热处理5 min条件下锡铋合金的填充效果最佳,端面硬度、轴向、径向导热率达到最高值62.65 HD、0.5324和0.2987 W/(m·K)。木材内部肉豆蔻酸的留存率介于27.54%~63.68%之间,经过160℃热处理3 min后储能密度最高(59.38 J/cm3)。【结论】高低温交替热处理促使锡铋合金进入到木材的导管内,实现了不同程度的渗透。木材的三维孔隙结构与外层填充的锡铋合金解决了相变材料的液体泄漏及导热性差问题。制备的储能木材综合了木材、金属与相变材料的优势,具有更优异的端面硬度、顺纹抗压强度与热性能,有望应用于建筑墙体和储能地板等领域。

强磁场对Bi-Mn合金半固态凝固过程中MnBi析出相组织的影响

在Bi 6%Mn合金从高于355℃(升温过程中MnBi化合物磁性转变温度)的固液两相区凝固过程中,研究了MnBi析出相组织在无磁场和强磁场条件下的演化过程。结果表明:在无磁场条件下MnBi析出相形态在340℃(MnBi相顺磁铁磁转变温度)附近发生突变,由较规则的六方块状变为沿ab面长大的不规则片状;10T磁场条件下析出相形态突变的温度提高到355℃左右。另外,10T磁场能够控制析出相晶粒以c轴平行磁场取向、定向聚合和熔合长大,使析出相的最终形态又趋向较规则的六方块状。

Sn-0.3Ag-0.7Cu-xBi低银无铅钎料的润湿性

以Bi为添加剂对低银型Sn-0.3Ag-0.7Cu无铅钎料进行改性,应用SAT—5100型润湿平衡仪对Sn-0.3Ag-0.7Cu-xBi(x=0,1,3和4.5)钎料的润湿性能作了对比分析。结果表明:适量Bi元素的加入可以改善Sn-0.3Ag-0.7Cu钎料合金的润湿性能,且在240℃下Sn-0.3Ag-0.7Cu-3.0Bi无铅钎料具有最佳的润湿性能,在250℃其润湿力达到最大值3.2×10–3N/cm。

Bi—In合金熔体作用浓度的计算模型

本文从含化合物金属熔体的共存理论和相图出发,用回归分析法确定了Bi-In金属熔体中存在有Bi_5In_3,BiIn和BiIn_2三种化合物,推导了各组元的作用浓度计算模型.在673～4200K之间的不同温度下,计算的N_(In),N_(Bi)和实际的活度值完全符合.同时求得了生成各化合物的lgk—T关系式(673-1200K)为: 各化合物的标准生成自由能为:

Sn-Zn-Bi无铅焊料表面张力及润湿性研究

采用气泡最大压力法对Sn-9Zn-XBi焊料进行了表面张力测试,用平衡法测试焊料的润湿性。结果表明:Bi的添加大大降低了Sn-Zn系焊料熔体的表面张力;然而焊料暴露在空气环境下1min后,表面形成ZnO导致其表面张力增大;Bi的增加提高了焊料在铜片上的润湿力,缩短了润湿时间;Sn-9Zn-XBi焊料润湿力仍低于Sn-40Pb,其原因是焊料–铜界面能偏高。