Influence of strong heterocoordination on surface properties of Li–Pb melts

The influence of the strong heterocoordination tendency of the Li–Pb liquid alloy on its surface properties has been studied using a statistical thermodynamic model based on compound formation and that based on the layered structure near the interface. In addition to the already proposed saltlike structure Li₄Pb compound formed in the liquid alloy, the study shows that the compound Li₃Pb also has a profound influence on the thermodynamic properties of the liquid alloy. The surface study suggests that the formed compounds in the liquid alloy segregate to the surface about 0.8 atomic fraction of Li. The calculated surface tension of the liquid alloy exhibits a pronounced hump above equiatomic composition.     

稀土元素取代对Ti_(0.26)Zr_(0.07)V_(0.24)Mn_(0.1)Ni_(0.33)贮氢合金结构和电化学性能的影响

研究了5种稀土元素部分取代V对Ti0.26Zr0.07V0..24Mn0.1Ni0.33合金的微观结构和电化学性能的影响。结果表明,Ti0.26Zr0.07V0.24Mn0.1Ni0.33和Ti0.26Zr0.07V0.24-xMn0.1Ni0.33REx(x=0.005;RE=La,Ce,Nd,Ho,Y)均由体心立方结构的钒基固溶体相和六方结构的C14 Laves相组成。在合金中加入稀土元素,会使合金中两相的晶胞体积同时增大。稀土元素部分取代V均改善了合金电极的活化性能。La和Nd元素取代后,合金电极的最大放电容量明显增加,而Ce的取代提高了合金电极的循环稳定性。Ce,Nd,Ho,Y均改善了合金电极的倍率放电性能。合金电极在高温状态下表现出了良好的放电性能,其中Nd在333 K时放电容量可达550.4 mAh·g-1。稀土元素对荷电保持率的影响各异。     

稀土元素取代对Ti0.26Zr0.07V0.24Mn0.1Ni0.33贮氢合金结构和电化学性能的影响

研究了5种稀土元素部分取代V对Ti_0.26Zr_0.07V_0..24Mn_0.1Ni_0.33合金的微观结构和电化学性能的影响。结果表明,Ti_0.26Zr_0.07V_0.24Mn_0.1Ni_0.33和Ti_0.26Zr_0.07V_0.24-xMn_0.1Ni_0.33RE_x（x=0.005;RE=La,Ce,Nd,Ho,Y）均由体心立方结构的钒基固溶体相和六方结构的C14Laves相组成。在合金中加入稀土元素,会使合金中两相的晶胞体积同时增大。稀土元素部分取代V均改善了合金电极的活化性能。La和Nd元素取代后,合金电极的最大放电容量明显增加,而Ce的取代提高了合金电极的循环稳定性。Ce,Nd,Ho,Y均改善了合金电极的倍率放电性能。合金电极在高温状态下表现出了良好的放电性能,其中Nd在333K时放电容量可达550.4mAh·g^-1。稀土元素对荷电保持率的影响各异。     

Phase structure and morphology of zinc-iron alloy electrodeposits

Zinc-iron alloy electrodeposits are providing higher corrosion resistance to steel components and also having better mechanical properties when compared to zinc deposits. This is due to the unique phase structure of the alloy formed. This study elucidates the phase structure of the electrodeposited alloy, based on the deposition kinetics and morphological characteristics. Deposition of iron was hindered by charge-transfer process, at low current densities. But zinc deposition was prevailed through diffusion control, only at high current densities. The probability of substitution of iron in hcp lattice along c-axis is more, than a-axis. This is because the linear density along c-axis is lower than a-axis. Intermetallic compounds of variable compositions were identified. Compounds such as FeZn₁₆, FeZn₁₃, Fe₅Zn₇₈ have dominantly “η” phase structure and FeZn₆, Fe₅Zn₂₂, Fe₂Zn₇, Fe₅Zn₂₉, Fe₃Zn₁₃ have “Γ” phase structure.     

Short range order in molten Al–Si alloys

We have studied the microscopic structure such as, concentration fluctuation in long wavelength limit (S_CC(0)), Warren–Cowely short range order parameter (α ₁), ratio of mutual and intrinsic diffusion coefficients (D _M/D _id) of molten Al–Si alloy at 1700?K using a statistical model of complex formation on the basis of quasi-lattice theory for weakly interacting systems. The approach used in this article reveals that molten Al–Si alloy at 1700?K is a weakly interacting heterocoordinating system and the alloy is more ordered in the Al-rich end.     

Thermodynamic and structural investigations of liquid magnesium-thallium alloys

The thermodynamic and microscopic structure of MgTl liquid alloy at 923 K has been studied by using regular associated solution model. The free energy of mixing, heat of mixing, entropy of mixing, activity, concentration fluctuations in long-wavelength limit S_CC(0) and the Warren-Cowley short-range parameter α₁ have been determined. The analysis suggests that this alloy is of a moderately interacting nature. The theoretical analysis reveals that the pairwise interaction energies between the species depend on temperature and there is a tendency of unlike atoms pairing (Mg-Tl) in liquid MgTl alloys at all concentration. The observed asymmetry in the properties of mixing of MgTl alloy in molten state is successfully explained by assuming MgTl complex on the basis of regular associated solution model.     

Catalytic Performance and Dispersion Behavior of Supported Nano‐Amorphous Alloy NiB/MCM‐41 Catalysts Prepared by Chemical Reductive Deposition

Supported nano‐amorphous alloy NiB/MCM‐41 catalysts were prepared by chemical reductive deposition. The as‐prepared catalysts were characterized by XRD, SEM, TEM, EDAX, ICP, and N₂ adsorption‐desorption. The amorphous alloy structure of NiB active sites, mesoporous structure of catalysts, and higher BET area have been proved by the experiments. The catalysts have given excellent catalytic activity and selectivity in the production of 3‐(N‐benzyl)‐amino‐4‐methoxy‐ acetanilide from 3‐amino‐4‐methoxy‐acetanilide and benzaldehyde.     

Structural and energetic asymmetry in liquid Ag–Al alloys

The thermodynamic and microscopic structure of Ag–Al liquid alloy at 1273?K has been studied by using regular associated solution model. This model has been utilised to determine the complex concentration in a regular associated solution of Ag and Al. We have then used the complex concentration to calculate the free energy of mixing, enthalpy of mixing, entropy of mixing, activity and concentration fluctuations in long wavelength limit S _CC(0) and the Warren–Cowley short-range parameter α ₁. The analysis suggests that heterocoordination leading to the formation of complex Ag₃Al is likely to exist in the liquid but is of a weakly interacting nature. The theoretical analysis reveals that the pairwise interaction energies between the species depend considerably on temperature and the alloy is more ordered towards Ag-rich region. The alloy behaves like a segregating system in Al-rich region.     

Properties of nanocrystalline electrodeposited CoFeP alloy with low phosphorus content

CoFe and low phosphorus containing (<4 at.%) CoFeP alloy films were electrodeposited from NaH₂PO₂ containing solutions at pH 4 on copper substrates under galvanostatic conditions. At the low phosphorus composition, nanocrystalline CoFeP alloy films are formed. The structure, composition and morphology of the thin films were studied using X-ray diffraction, energy dispersive spectroscopy and atomic force microscopy. The magnetic properties of the film were studied using superconducting quantum interference device magnetometer. The thin film performance features were explained on the basis of microstructural features developed during deposition. Whereas the electrodeposited CoFe alloy thin film exhibited mixed hcp and fcc phase structure in the absence of phosphorus, the low phosphorus containing thin film exhibited an increasing mixed bcc and hcp phase structure as its phosphorus content increases, showing modification in the grain size morphology and magnetic properties. In addition to applied current, the amount of P co-deposited in CoFeP alloy depends on the concentration of NaH₂PO₂ source in the bath. Qualitative analysis of the Tafel slope of CoFe and CoFeP deposition suggests that the presence of P in the CoFe deposit does not affect the mechanism of anomalous deposition of Co and Fe, thereby suggesting that CoFeP deposition is anomalous.     

Effects of Ti and Co on the Electrochemical Characteristics of MgNi-Based Alloy Electrodes

Mg-based hydrogen storage alloys MgNi, Mg0.9Ti0.1Ni and Mg0.9Ti0.1Ni0.9Co0.1 were successfully prepared by means of mechanical alloying （MA）. The structure and the electrochemical characteristics of these Mg-based materials were also studied. The results of X-ray diffraction （XRD） and scanning electron microscopy （SEM） show that the main phases of the alloys exhibit amorphous structures, and trace of Ni co-exists. The charge-discharge cycle tests indicate these alloys have good electrochemical active characteristics. And the cycle stability of Ti and Co doped alloy was better than that of MgNi alloy. After 50 cycle charge-discharge, the discharge capacity of the Mg0.9Ti0.1Ni0.9Co0.1 alloy was much better than that of MgNi and Mg0.9Ti0.1Ni alloys. The discharge capacity of Mg0.9Ti0.1Ni0.9Co0.1 was 102.8% higher than that of MgNi alloy, and 45.49% higher than that of the Mg0.9Ti0.1Ni alloy. During the process of charge-discharge cycle test, the main reason for the electrode capacity fading is the corrosion of Mg to Mg（OH）2 on the surface of alloys. The Tafel polarization test indicates Ti and Co improve the anticorrosion in an alkaline solution. The EIS results suggest that proper amount of Ti and Co doping improve the electrochemical catalytical activity on the Mg-based alloy surface significantly.     

Thermal studies for preparation of Nb10Hf1Ti Alloy

The aim of this work is to evaluate the feasibility of preparation of Nb10Hf1Ti alloy by magnesiothermic reduction of its oxides. DTA studies were conducted to identify the reduction temperature for co reduction of the mixed oxides of Nb₂O₅, HfO₂, and TiO₂ by magnesium under reducing atmosphere. Based on DTA analysis, experiments were carried out to prepare Nb10Hf1Ti alloy by magnesiothermic reduction of their oxides at 750 °C. The reduced product was analyzed for its phases by X-ray diffraction. The excess Mg was leached out, the alloy mixture was vacuum dried, pelletized, sintered, and electron beam melted to get a consolidated alloy of the required composition. The alloy was characterized using different techniques such as optical microscopy, scanning electron microscopy, and chemical analysis. Microstructural observations revealed the formation of coarse grain structure in the consolidated alloy. The alloy product was also evaluated for its micro hardness.     

Thermal analysis,crystal structure and magnetic properties of Cr-doped Ni–Mn–Sn high-temperature magnetic shape memory alloys

The superiority of NiMnSn alloy on NiMnGa alloy is far ahead in term of some physical characteristics, and therefore, the development of this alloy group is very important. In this work, Ni₅₀Mn_45−xSn₅Cr_x magnetic shape memory alloys were produced for x = 0, 4, 6, 10 and 12. Thermal analysis was performed on produced alloys in a wide range (200–1000 °C) by using differential scanning calorimetry, thermogravimetric and differential thermal analysis. According to the thermal analysis results, the austenite ↔ martensite transformation temperatures of the NiMnSn alloy decreased with increasing chromium content. Furthermore, the increase in the chromium ratio caused single-phase transformation due to the multiple phase transformation that was observed in the NiMnSn alloy. In addition, the crystal structure and microstructure analyses of the alloys were determined by using X-ray diffraction and scanning electron microscopy–energy-dispersive X-ray spectroscopy. In all cases, martensite and gamma phase were encountered and the gamma phase ratio was found to be increased by chromium addition. The magnetization characteristics were studied by using physical properties measurement systems device, and it was found that the alloys have a considerably small response to magnetic flux.

     

PPy‐encapsulated SnS2 Nanosheets Stabilized by Defects on a TiO2 Support as a Durable Anode Material for Lithium‐Ion Batteries

Nanostructured‐alloy‐type anodes have received great interest for high‐performance lithium‐ion batteries (LIBs). However, these anodes experience huge volume fluctuations during repeated lithiation/delithiation and are easily pulverized and subsequently form aggregates. Herein, an efficient method to stabilize alloy‐type anodes by creating defects on the surface of the metal oxide support is proposed. As a demonstration, PPy‐encapsulated SnS₂ nanosheets supported on defect‐rich TiO₂ nanotubes were produced and investigated as an anode material for LIBs. Both experimental results and theoretical calculations demonstrate that defect‐rich TiO₂ provides more chemical adhesions to SnS₂ and discharge products, compared to defect‐poor TiO₂, and then effectively stabilizes the electrode structure. As a result, the composite exhibits an unprecedented cycle stability. This work paves the way to designing durable and active nanostructured‐alloy‐type anodes on oxide supports.     

稀土元素对Ti0.26Zr0.07V0.24Mn0.1Ni0.33贮氢合金微观结构和电化学性能的影响

本文研究了稀土元素对Ti0.26Zr0.07V0.24Mn0.1Ni0.33合金的微观结构和电化学性能的影响。结果表明,Ti0.26Zr0.07V0.24-xMn0.10Ni0.33REx(RE=Ce,Nd,Gd;x=0.01)合金均有V基固溶体相和C14型Laves相两相组成。合金中两相的晶格参数随加入稀土元素的不同而发生变化。稀土元素部分取代可改善合金电极的活化性能。然而,对合金电极的其他性能影响因元素种类不同而各异。Ce取代增大了合金电极的最大放电容量,Nd元素可以有效改善合金的高倍率放电性能。工作温度对合金电极的放电容量影响较大,Nd和Gd在333 K最大放电容量可达426和465 mAh.g-1。过高的温度使其循环容量衰减加剧。     

Study on corrosion resistance of electroplating zinc–nickel alloy coatings

Electrodeposited zinc–nickel alloy coatings have been widely adopted for surface treatment of automobile body steel sheet for high corrosion resistance. The corrosion behavior of the coatings has been related with the components of nickel, and the zinc–nickel alloy passive coatings have much higher corrosion resistance than that of zinc–nickel alloy coatings. In the present paper, the corrosion resistance behavior of the zinc–nickel alloy coatings obtained by new process and formulation has been studied by means of the electrochemistry test and neutral salt spray test. And it is discovered that the properties of corrosion resistance of zinc–nickel alloy passive coatings were better than that of zinc passive coatings, Cadmium passive coatings and alloys of electrodeposited cadmium–titanium. The components of corrosion productions, in terms of X‐ray diffraction (XRD), are mainly ZnO, ZnCl₂ · 4Zn(OH)₂ and small quantity of 2ZnCO₃· 3Zn(OH)₂. The component of zinc–nickel alloy coatings has been investigated with Glow Discharge Optical Emission Spectrometry (GDA‐750). And it is found that as the thickness of zinc–nickel alloy coatings increases, the component of zinc increases from beginning to end, but the peak value of nickel appears and an enrichment of nickel in the coatings comes into being. Because the electrodeposited zinc–nickel alloy coatings exhibit different alloy phases as a function of their alloy composition, in this paper, the crystal structure changing with the different component of nickel has been studied in terms of XRD. The result shows that electrodeposited zinc–nickel alloy has different phases: α‐phase, a solid solution of zinc in nickel with an equilibrium solubility of about more than 79% nickel; γ‐phase, an intermediate phase with a composition Ni₅Zn₂₁; η‐phase, a solid solution of nickel in zinc with less than 5% nickel; and δ‐phase (Ni₃Zn₂₂) appeared from η‐phase to α‐phase with increasing content of nickel. Copyright © 2009 John Wiley & Sons, Ltd.     

Oxidation of carbon monoxide and formic acid on bulk and nanosized Pt–Co alloys

Bulk Pt₃Co and nanosized Pt₃Co and PtCo alloys supported on high area carbon were investigated as the electrocatalysts for the CO_ads and HCOOH oxidation. Pt₃Co alloy with Co electrochemically leached from the surface (Pt skeleton) was employed to separate electronic from ensemble and bifunctional effects of Co. Cyclic voltammetry in 0.1 M HClO₄ showed reduced amount of adsorbed hydrogen on Pt sites on Pt₃Co alloy compared to pure Pt. However, no significant difference in hydrogen adsorption/desorption and Pt-oxide reduction features between Pt₃Co with Pt skeleton structure and bulk Pt was observed. The oxidation of CO_ads on Pt₃Co alloy commenced earlier than on Pt, but this effect on Pt₃Co with Pt skeleton structure was minor indicating that bifunctional mechanism is stronger than the electronic modification of Pt by Co. The HCOOH oxidation rate on Pt₃Co alloy was about seven times higher than on bulk Pt when the reaction rates were compared at 0.4 V, i.e., in the middle of the potential range for the HCOOH oxidation. Like in the case of CO_ads oxidation, Pt skeleton showed similar activity as bulk Pt indicating that the ensemble effect is responsible for the enhanced activity of Pt₃Co alloy toward HCOOH oxidation. The comparison of CO_ads and HCOOH oxidation on Pt₃Co/C and PtCo/C with the same reaction on Pt/C were qualitatively the same as on bulk materials.     

Electrodeposition and electrochemical properties of novel ternary tin–cobalt–phosphorus alloy electrodes for lithium-ion batteries

Porous Sn–Co–P alloy with reticular structure were prepared by electroplating using copper foam as current collector. The structure and electrochemical performance of the electroplated porous Sn–Co–P alloy electrodes were investigated in detail. Experimental results illustrated that the porous Sn–Co–P alloy consists of mainly SnP_0.94 phase with a minor quantity of Sn and Co₃Sn₂. Galvanostatic charge–discharge tests of porous Sn–Co–P alloy electrodes confirmed its excellent performances: at 50th charge–discharge cycle, the discharge specific capacity is 503 mAh g^?1 and the columbic efficiency is as high as 99%. It has revealed that the porous and multi-phase composite structure of the alloy can restrain the pulverization of electrode in charge/discharge cycles, and accommodate partly the volume expansion and phase transition, resulting in good cycleability of the electrode.     

Ti0.17Zr0.08V0.34Nb0.01Cr0.1Ni0.3氢化物电极合金微观结构及电化学性能研究

采用XRD、FESEM-EDS、ICP及EIS等方法研究了Ti_0.17Zr_0.08V_0.34Nb_0.01Cr_0.1Ni_0.3氢化物电极合金微观结构和电化学性能。X射线衍射分析表明：该合金由体心立方结构(bcc)的V基固溶体主相和少量六方结构的C14型Laves相组成；FESEM及EDS分析表明：V基固溶体主相形成树枝晶，C14型Laves相呈网格状围绕着树枝晶的晶界，元素在两相中的分布呈现镜像关系。电化学性能测试结果表明：该合金的氢化物电极在303~343 K较宽的温度区间内，表现出较高的电化学容量，在303 K和343 K时，电化学容量分别为337.0 mAh·g^-1和327.9 mAh·g^-1。在303 K循环100周后，容量为282.7 mAh·g^-1。ICP分析结果表明，氢化物电极在充放电循环过程中，V及Zr元素向KOH电解质中的溶出较为严重。EIS研究表明，金属氢化物电极表面电化学反应的电荷转移电阻(R_T)随循环次数的增加而增加，相应的交换电流密度则随循环次数的增加而降低。氢化物电极循环过程中RT的增大以及V和Zr元素的溶解，可能是导致电极容量衰减的主要原因。     

Formation of a tetragonal Cu3Au alloy at gold/copper interfaces

A gold–copper alloy with a nominal composition of Cu₃Au but with a tetragonal (c = 4a) structure is observed to form at Au/Cu interfaces of gold/copper multilayers deposited on amorphous substrates by d.c. magnetron sputtering. The formation of this non‐equilibrium structure (tentatively D0₂₃) under‐ambient conditions is detected by secondary ion mass spectrometry, x‐ray diffraction and high‐resolution cross‐sectional transmission electron microscopy. Co‐sputtering of Au and Cu under similar conditions produces only conventional fcc Cu₃Au alloy phases, suggesting that interfacial confinement plays a significant role in producing the novel Cu₃Au alloy phase in gold/copper multilayers. Copyright © 2003 John Wiley & Sons, Ltd.     

2D MOF-assisted Pyrolysis-displacement-alloying Synthesis of High-entropy Alloy Nanoparticles Library for Efficient Electrocatalytic Hydrogen Oxidation

Multimetallic alloy nanoparticles (NPs) have received considerable attention in various applications due to their compositional variability and exceptional properties. However, the complexity of both the general synthesis and structure–activity relationships remain the long-standing challenges in this field. Herein, we report a versatile 2D MOF-assisted pyrolysis-displacement-alloying route to successfully synthesize a series of binary, ternary and even high-entropy NPs that are uniformly dispersed on porous nitrogen-doped carbon nanosheets (PNC NSs). As a proof of utility, the obtained Co_0.2Ru_0.7Pt_0.1/PNC NSs exhibits apparent hydrogen oxidation activity and durability with a record-high mass specific kinetic current of 1.84 A mg⁻¹ at the overpotential of 50 mV, which is approximately 11.5 times higher than that of the Pt benchmark. Both experimental and theoretical studies reveal that the addition of Pt engenders a phase transition in CoRu alloys from hexagonal close-packed (hcp) to face-centered cubic (fcc) structure. The elevated reactivity of the resulted ternary alloy can be attributed to the optimized adsorption of hydrogen intermediate and the decreased reaction barrier for water formation. This study opens a new avenue for the development of highly efficient alloy NPs with various compositions and functions.