Ni System Research Articles

Metallaphotocatalytic Amination of Aryl Chlorides Enabled by Highly Crystalline Acetylene-Based Hydrazone-Linked Covalent Organic Frameworks.

Amination of aryl chlorides by metallaphotocatalysis is highly desired but remains practically challenging. Meanwhile, relying on soluble noble-metal photocatalysts suffers from resource scarcity and structural instability which limit their practical application. Here in, a highly crystalline acetylene-based hydrazone-linked covalent organic framewok-1 (AC-COF-1) is reported that enables metallaphotocatalytic amination of aryl chlorides. The non-planar effect of hydrazone linkage and weak interlayer attraction of acetylene bond are minimized by intralayer hydrogen-bonding. As a result, the COF shows not only improved crystallinity and porosity, but also enhanced optical and electronic properties compared to a COF analog without hydrogen-bonding. Notably, dual AC-COF-1/Ni system affords CN coupling products from broad aryl chloride substrates in excellent yields (up to 99%) and good functional tolerance. Furthermore, AC-COF-1 is recoverable and reusable for seven times photocatalysis cycles. This report demonstrates simple approach to tune the structure-activity relationship in COFs at molecular level.

Processes of formation of Cu–Ni alloy films by electron beam evaporation

The features of the formation of Cu–Ni alloy films by electron beam evaporation are considered. The position of the isobars of the total pressure of copper and nickel on the state diagram of the Cu–Ni during evaporation in vacuum is determined. Calculations of the elemental compositions of films have been carried out. It is shown that the nickel content in films deposited during boiling of Cu50Ni50 alloy in vacuum is 50 times less than in the alloy. The structure and elemental composition of the surface layer of alloys after their evaporation and sublimation, as well as the elemental composition of the deposited films, are investigated. It is shown that the most acceptable way to obtain films of stable composition in the Cu–Ni system is simultaneous electron beam evaporation of copper and nickel from two crucibles.

Structural and spectroscopic study of the kieserite-type (Mg,Mn)SO4·H2O solid solution at ambient and low temperatures relevant to Mars and the icy moons of Jupiter and Saturn

The presence and importance of sulfates in our solar system have become common knowledge among the dedicated scientific community, as well as their crucial role in governing the water budget of planets such as Mars. The formation of subsurface oceans and cryovolcanism on icy moons of Jupiter and Saturn owe their existence to melting equilibria influenced by sulfate hydrates in the deeper parts of these celestial bodies. In such a setting, it cannot be ruled out that lower-hydrated sulfates including kieserite, MgSO4·H2O, are also present, given their stability under geologic pressures relevant even down to the lower mantle of the icy satellites. With regard to the composition of the water-soluble fraction in C1 and C2 chondritic meteorites presumed to correspond to that of the rocky cores of the Jovian moons, local kieserite may contain significant amounts of Mn in addition to Ni (and also some Fe). Minor Mn contents are probable even in kieserite occurring on the surface of Mars. Substantial lattice parameter changes and spectral band shifts between kieserite and its isostructural Mn-analogue szmikite, MnSO4·H2O, are well known, nevertheless neither the existence of a potential MgMn solid solution series nor its crystal chemical and spectroscopic behavior has yet been investigated.This work provides the first evidence for such a continuous solid solution, describes its structural properties, and gives a detailed insight into the position changes of prominent bands in FTIR- and Raman spectra of synthetic samples, as the Mn/Mg ratio increases, with the measurement having been performed both at ambient and low temperatures relevant for Mars and the icy satellites. It reveals that contents of Mn do not cause any significant shift in the H2O stretching vibrational bands, yet influence the position of sulfate-related vibrations much in the same way as the incorporation of other relevant transition metal cations, such as Ni. The contrasting behavior of the ν3 and ν1 stretching vibrations of the H2O molecule in case of Mn- (no shift) and Ni-incorporation (significant shift to lower wavenumber) along with their comparable influence on the position of sulfate bands allow to deduce the chemical composition of kieserite in a ternary Mg–Mn–Ni system based on spectroscopic remote sensing or in situ data from celestial bodies. The assessment of chemical composition from vibrational spectra is facilitated by the observed Vegard-type behavior, where lattice parameters as well as the spectral band positions change along linear trends with increasing substitution of Mg, regardless if by Mn, Fe, or Ni. The observed shift of mainly the H2O stretching vibrations to lower wavenumber values as temperature decreases (in contrast to the bands related to the sulfate group) match thermal behavior observed in other binary solid solutions of sulfate monohydrate phases isostructural with kieserite.

The influence of Ni on the composition, structure and properties of Ti-Cr-N coatings

The influence of nickel on the structure and properties of Ti-Cr-N ion-plasma coatings obtained by arc-PVD method has been studied. With a nickel content of up to 11.9 at. %, the coating consists of Cr2N, Ti1 – xCrxN, and metallic Ni. Upon further increase in Ni concentration in the coating, intermetallic compound Ni3Ti is formed. The structure of the coatings was studied using the transmission electron microscopy. The coatings of Ti-Cr-N system are characterized by a columnar structure, in the columns of which Ti1 - xCrxN and Ti1 - yCryN (x > y) sublayers, being several nanometers thick and containing variable concentration of titanium and chromium, as well as Cr2N sublayers of about 25 nm are formed due to the complete solubility of TiN and Cr2N and the planetary rotation of the substrates, resulting in layer-by-layer stacking of the components of the evaporated cathodes. This structure remains intact in coatings of Ti-Cr-N-Ni system with a low nickel concentration (on the order of tenths of at. %). However, upon that, the column size refinement and an increase in biaxial compressive stresses from 6.7 to 9.7 GPa are observed, which results in an increase in hardness from 30 to 42 GPa. The coatings with a high nickel content are characterized by a multilayer architecture with an equiaxed polycrystalline structure of nanograins in layers. As Ni concentration increases, the hardness of the coating decreases to 16.7 GPa, which is associated with an increase in the fraction of relatively soft nickel in the coating and a decrease in macrostresses to -0.6 GPa. Upon that, the wear intensity increases from 3·10-15 to 5·10-15 m3/(N·m). The studied coatings of Ti–Cr–N and Ti–Cr–N–Ni systems are resistant to adhesive and cohesive destruction. With an increase in the nickel content upon measuring scratching, the destruction of the coatings occurs exclusively due to the plastic deformation.

Diffusion kinetics for fcc quinary Cu–Co–Mn–Ni–Si system and its application to precipitation simulations

The accurate diffusivity and kinetic database of fcc quinary Cu–Co–Mn–Ni–Si system is essential for designing high-performance Cu alloys, which is still not investigated yet. In the present work, on the basis of the critically reviewed experimental diffusivities available in the literature, the atomic mobilities of fcc Mn–Ni and Cu–Mn–Ni alloys were re-assessed through CALTPP (CALculation of ThermoPhysical Properties) program, aiming to establish a self-consistent kinetic database for fcc Cu–Co–Mn–Ni–Si system. Comparing the model-calculated diffusion coefficients, composition profiles and diffusion paths with the measured ones for fcc Mn–Ni and fcc Cu–Mn–Ni alloys, it is found that the experimental data are reasonably reproduced by the re-assessed atomic mobilities, indicating their good reliability. Therefore, integrating the presently obtained atomic mobilities for the fcc Mn–Ni and fcc Cu–Mn–Ni systems with those for other sub-systems, a complete kinetic database for fcc Cu–Co–Mn–Ni–Si system was established for the first time. The reliability of the constructed kinetic database was confirmed by the reasonable agreements between the model-predicted composition profiles of sub-quaternary and quinary diffusion couples and the measured ones. Furthermore, this obtained kinetic database was applied to simulate the microstructure evolution of second-phase precipitates in Cu–Mn–Ni, Cu–Ni–Si and Cu–Ni–Co–Si alloys during the aging process, and the simulated results demonstrate good agreements with the experimental ones. The present work indicates the reliability and significance of the presently obtained kinetic database of fcc quinary Cu–Co–Mn–Ni–Si system for predicting the microstructure evolution during the heat treatment process, which can greatly contribute to the design of Cu alloys with high performance.

Circular Recycling Strategies for LFP Batteries: A Review Focusing on Hydrometallurgy Sustainable Processing

The exponential growth of electric and hybrid vehicles in the last five years forecasts a waste problem when their batteries achieve end-of-life. Li-ion batteries for vehicles have been assembled using materials from natural resources (as Li, Fe, Al, Cu Co, Mn and P). Among them, LiFePO4 cathode materials have demonstrated advantages such as charge–discharge cycles, thermal stability, surface area and raw materials availability (against Ni and Co systems). Due to the performance, LFP batteries stand out in heavy duty fleet, achieving 90% of new energy buses in China. To achieve the circular economy, the recycling of LFP batteries may be carried out by pyrometallurgy (thermal processing), hydrometallurgy (aqueous processing) or both in combination. Comparatively, hydrometallurgical processing is more advantageous due to its low energy consumption and CO2 emissions. In addition, Li may be recovered in a high-pure grade. This work is a literature review of the current alternatives for the recycling of LFP batteries by hydrometallurgy, comparing designed processes in the literature and indicating solutions towards a circular economy. The major recycling steps of hydrometallurgy routes such as pre-treatments, leaching and purification steps will be gathered and discussed in terms of efficiency and environmental impact.

Understanding the yield strength difference in dual-phase eutectic high-entropy alloys

Face-centered cubic (FCC)/ordered body-centered cubic (B2)-structured Al–Co–Cr–Fe–Ni system eutectic high-entropy alloys (EHEAs) have a favorable combination of high strength and ductility in the as-cast state. However, the mechanical properties of this type of alloy vary significantly with composition. In this study, we attempted to determine the yield strength differences in FCC/B2 EHEAs. Based on reported Al0.8CrFeNi2.2, we successfully prepared three low-cost Co-free EHEAs: Al0.82Cr0.8Fe1.2Ni2.18, Al0.83Cr0.6Fe1.4Ni2.17, and Al0.85Cr0.4Fe1.6Ni2.15. All the EHEAs are shown to exhibit the same phase constituent (FCC/B2) and complete eutectic microstructure, with similar lamellar thickness but different tensile properties. We constructed a theoretical calculation model based on the Hall-Petch regime which fits the measured yield strength σ0.2. The yield differences for current FCC/B2 EHEAs results mainly from different intrinsic strengths of their soft FCC phases.

Tuning the electronic properties of WS2 monolayer by doping transition metals: DFT Approach

TMDS is considered for many possible applications in different fields such as electronics, spintronics, optoelectronics, photocatalytic and photovoltaic devices on account of their superior characteristics. In this current study, we have explored the stability and the electronic characteristics of monolayer WS2 and nXWS2 (n = 1,2,3 and X = Fe, Co, Ni) systems using density functional theory (DFT). The system's stability has been calculated using the formation energy. The electronic characteristics of the systems are studied by band structure, chemical potential, chemical shift, total energy, charge transfer, formation energy, the density of states and the projected density of states of the systems. The formation energy calculation results that the nXWS2 system has greater stability than the monolayer WS2 system. The electronic property is enhanced by substituting the dopants in higher concentrations. We observed that the nFeWS2 and nCoWS2 systems possess p-type nature. The nNiWS2 system exhibits n-type nature for concentrations one and two but for the third concentration, the system slowly changes to p-type nature. These outcomes propose that the use of such dopants with higher concentrations can give a method for changing the electronic properties of the TMDS for nanoelectronics and sensing applications.

Progress toward a better understanding of the urea oxidation by electromediation of Ni(III)/Ni(II) system in alkaline media

Current treatments of wastewater containing urea are energy intensive and release significant quantities of gaseous nitrous oxide. The anodic oxidation of urea by electromediation of Ni(III)/Ni(II) system in alkaline media is a promising alternative: the nitrogenous pollution is decreased while producing hydrogen at the cathode. Firstly, this study aims to deeply investigate the phenomena occurring at the interface, between electrode and electrolyte, in particular by proposing an original methodology enabling to separately study both steps,i.e. the Ni(II) electro-oxidation and the subsequent indirect heterogeneous urea oxidation. Indeed, the variation the potential scan rate, enables (i) to study the effect of the operating parameters (concentration, temperature, angular velocity of a rotating disk electrode) on the rate of each mechanism step, and to (ii) determine key parameters of the overall process (activation energy, diffusion coefficient, anodic charge transfer coefficient and heterogeneous electron transfer rate constant). In a second time, results of urea electrolysis exhibiting high (∼ 80%) urea conversions, carried out at laboratory scale (1.4 g of urea) are discussed. The effect of some operating parameters (alkalinity, temperature, presence of an anionic separator or not) is examined, thanks to a set of analytical methods developed to establish complete mass balances of the products on the liquid phase. Cyanate, ammonium, carbonate and nitrite ions are identified to represent more than 80 % of the destroyed urea. Their respective quantities appear to be dependent of the operating conditions. This study constitutes an essential preliminary step before designing urea electrochemical process operating at larger scale.

Utilization of γ-radiation in the synthesis of bimetallic Cu–Ni catalysts for selective vapour phase hydrogenation of levulinic acid to γ-valerolactone

A set of mono and bimetallic Cu–Ni systems supported on γ-alumina catalysts were synthesized using γ-radiation instead of conventional calcination and reduction.

Accelerating the design of high-entropy alloys with high hardness by machine learning based on particle swarm optimization

Combining a machine-learning (ML) surrogate model with a particle swarm optimization (PSO) algorithm, we propose a design strategy to search for high-entropy alloys (HEAs) with high hardness in the Al–Co–Cr–Cu–Fe–Ni system. The relationship between various materials descriptors and a targeted property can be established by the ML models based on the data set, which contains the mole fraction of each element. In this study, we use random forest (RF) to rank the feature importance based on the materials descriptors. It shows that the valence-electron concentration (VEC) and atomic-size difference (δ) are the two most critical factors to the hardness. The random forest combined particle swarm optimization is proposed to design the HEAs with high hardness in a search space containing nearly 65,000 data for the Al–Co–Cr–Cu–Fe–Ni system. We present the top 10 HEAs with high hardness, which are greater than the existing alloys in this HEAs system.

A high-dimensional neural network potential for molecular dynamics simulations of condensed phase nickel and phase transitions

ABSTRACT A high-dimensional neural network interatomic potential was developed and used in molecular dynamics simulations of condensed phase Ni and Ni systems with liquid–solid phase coexistence. The reference data set was generated by sampling the potential energy surface over a broad temperature-pressure domain using ab initio MD simulations to train a unified potential. Excellent agreement was achieved between bulk face-centred cubic nickel thermal expansion simulations and relevant experimental data. The same potential also yields accurate structures and diffusivities in the liquid state. The phase transition between liquid and solid phases was simulated using the two-phase interface method. The predicted melting point temperature is within a few kelvins of the literature value. The general methodology could be applied to describe crystals with much more complex phase behaviours.

Examination of the catalytic effect of Ni, NiCr, and NiV catalysts prepared as thin films by magnetron sputtering process in the hydrolysis of sodium borohydride

In this study, nickel, nickel-chromium alloy, and nickel-vanadium alloy were coated to form a thin film on the slides prepared by magnetron sputtering process, which were used as a catalyst for the hydrolysis of alkaline sodium borohydride. Factors, such as the temperature of the solution, amount of the catalyst, initial pH of the solution and the performance of these catalysts on hydrogen generation rate were investigated using response surface methodology. Moreover, the catalysts were characterized using XRD and FE-SEM/EDS analyses. Utilizing the obtained optimum conditions of the response surface methodology estimation, the maximum hydrogen generation rate was 35,071 mL min−1 gNiV−1 from NiV catalyst at 60 °C, pH 6, and 1.75 g catalyst conditions. Under the same experiment conditions, the maximum hydrogen generation rates of Ni and NiCr catalyst systems are 28,362 mL min−1 gNi−1, and 30,608 mL min−1 gNiCr−1, respectively.

Generalized method of sensitivity analysis for uncertainty quantification in Calphad calculations

Calculation of Phase Diagrams (Calphad) is a method of using thermodynamic models obtained from experimental data to perform thermodynamic calculations. The next step to advancing this methodology is to account for the inconsistency or lack of data when assessing thermodynamic systems. A generalized method of propagating uncertainty through Calphad calculations by local expansion is proposed such that any type of Gibbs free energy model or number of components can be used. This method is faster than Monte Carlo approaches as only a single equilibrium calculation is needed for uncertainty propagation and also improves upon previous approaches to uncertainty propagation by its generalization to any thermodynamic system. As a case study, the Mg–Si system was assessed using a Bayesian approach and various thermodynamic calculations were performed comparing uncertainty quantification by Monte Carlo and the method in this work. Sensitivities (derivatives with respect to model parameters) were calculated on the Fe–Cr–Ni system and compared with sensitivities determined by finite different method.

Simulation of BCC dissolution in Fe–Cr–Ni system by ICME

Simulation of BCC dissolution in Fe–Cr–Ni system by ICME

Influence of varying carbon content in (V,Nb,Ta,Ti,W)C high entropy carbide - Ni based cermets on densification, microstructure, mechanical properties and phase stability

The influence of varying carbon content on the microstructure and mechanical properties was studied in the (V,Nb,Ta,Ti,W)C - 12 vol% Ni system, allowing to define the carbon window for eta and graphite phase formation. Microstructure and phase analysis were performed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe microanalysis (EPMA), and the transverse rupture strength (TRS), Vickers hardness and Palmqvist fracture toughness were measured. The results elucidate the influence of the carbon content on the eutectic temperature, carbide grain size and morphology, phase stability and mechanical properties in high entropy carbide (V,Nb,Ta,Ti,W)C-Ni cermets. The phase stability and chemical reactivity with steel of the High Entropy Carbide (HEC) cermets was assessed in static interaction couples at 1200°C, and compared with that of a conventional WC-Co cemented carbide.

Potential of nickel nanoclusters supported on [formula omitted]-Al[formula omitted]O[formula omitted](0001) surface for CO[formula omitted] capture, energy production, and dry reforming of methane

The structural, electronic and magnetic properties of Nin@α-Al2O3(0001) (with n = 1 to 7) systems have been studied using density functional theory. Grafting energies, Bader charges and DOS analysis showed that the nickel clusters strongly interact with the α-Al2O3(0001) surface. In a second step, the adsorption performances of these materials towards CH4, CO2, CO, H2 gases have been evaluated. Pure alumina surface and supported Ni systems weakly interact with methane, which are therefore promising for an efficient purification of methane. Additionally, it was found that the pure alumina surface and Ni5/α-Al2O3(0001) selectively adsorb the CO2, facilitating its storage and utilization. A selective adsorption was also observed for CO on Ni3/α-Al2O3(0001). Looking now at the dry reforming of methane, a strong adsorption of CO was shown in all supported systems. The dissociative adsorption of hydrogen on all supported systems (except for n = 4) was observed. A high resistance against carbon deposition was observed on our modeled systems compared to those reported in the literature, which is a promising result since the rapid deactivation by coke deposition is the main problem for the catalysts used in the dry reforming of methane process.

Ball milling synthesis and effects of infrared heat treating on the nanocrystalline Ti/Zr/Cu/Ni system

A Ti/Zr based solid solution with a nominal wt. % composition of 37.5Ti-37.5Zr-15Cu-10Ni (eutectic) has been successfully synthesized by mechanical alloying using a high-energy planetary ball mill and it was performed at 250 rpm and different milling periods of 5, 10, and 15 h. Scanning electron microscopy revealed that the powder experienced severe deformation from the milling process. The powder was heat treated using an indigenous infrared tube furnace at a heating rate of 200 °C/min. X-ray diffraction results showed the presence of several nanocrystalline intermetallic compounds after infrared heat treating at 750 °C for 15 min in an argon atmosphere. The feature of infrared radiation ensured that the nanocrystalline size of the produced powder remained almost intact during the milling process. The crystal size, lattice parameter, and lattice strain at the optimal milling period (10 h) were determined to be 13 nm, 2.7 Å, and 0.4 %, respectively.

Experimental Investigation of Isothermal Section in the La–Co–Ni System at 723 K

The isothermal section of the La–Co–Ni ternary system at 723 K has been constructed in this work by using X-ray diffraction (XRD), scanning electron microscopy, and energy dispersion spectroscopy techniques (SEM-EDS). The experimental results show no existence of ternary compounds at 723 K. The isothermal section consists of 16 two-phase regions and 8 three-phase regions. La3Co and La3Ni, La2Co3 and La2Ni3, La2Co7 and La2Ni7, and LaCo5 and LaNi5 form a continuous solid solution. The ternary solid solubility of Ni in LaCo13 phase and La2Co1.7 phase was determined to be 15.61 at.% and 9.61 at.%, respectively. The solid solubility of Co in the LaNi3, La7Ni3, and LaNi phases was 18.07 at.%, 5.62 at.%, and 8.49 at.%, respectively. The present experimental results are important for the design of La(Fe,Si)13-based magnetic refrigeration materials.

Hall effect in Si/SiO2(Cu, Ni) low-dimensional inhomogeneous structures

The temperature and magnetic field dependences of the Hall effect are analyzed in the temperature range 20–300 K in magnetic fields up to 10 T in Si/SiO2 systems with magnetic (Ni) and nonmagnetic (Cu) metals in the pores of the silicon dioxide layer. It is shown that VH(Т) in the Si/SiO2(Cu, Ni) system has a complex character up to the inversion of the sign of VH, which is a consequence of the presence of various mechanisms of electrotransport. The substantiation of the difference between the dependences VH(Т) for various metals is given. It is shown that at low temperatures in systems with a ferromagnetic metal there is an anomalous contribution to the Hall electromotive force.