Ni System Research Articles

First-principles prediction of higher Curie temperature, metallic and half-metallic ferromagnetism in Zn1-x(Vx,Nix)O systems

The electronic and magnetic properties of Zn(V,Ni)O systems with 2.08 %, 4.16 %, 6.25 %, 8.3 %, and 12.5 % impurity concentrations were investigated based on ab initio simulations. The first-principles calculations were carried out using density functional theory and local spin density approximation by pseudopotential method. Analyzing the calculated density of states, the mechanism to stabilize the ferromagnetic phase in the 3d-metals doped ZnO systems is discussed. The analysis of the total density of states shows that the V-doped ZnO presents a metallic nature and Ni-doped ZnO exhibits a half-metallic character. First-principles calculations show that the stability of ferromagnetic or antiferromagnetic behaviors depends on impurity concentrations and impurity positions in related ZnO:V,Ni systems. Finally, we estimated and studied the Curie temperatures for V- and Ni-doped ZnO systems with different impurity concentrations. The Curie temperatures for VxZn1-xO and NixZn1-xO systems are higher than room temperature and these compounds are suitable ferromagnetic DMS materials for spintronic applications.

Hydrogen storage properties of Zr-based multicomponent alloys with C14-Laves phase structure derived from the Zr–Cr–Mn–Fe–Ni system

This study focused on assessing the crystal structure and hydrogen storage properties of two multicomponent alloys having the Zr33(CrMnFeNi)67 and Zr33Cr22Mn15Fe25Ni5 compositions. Both alloys were designed by thermodynamic calculations derived from the TiZrCrMnFeNi system after removing the titanium element from the original composition and keeping the high fraction of zirconium to explore new Zr-based compositions with a strong tendency to crystallize as a C14 Laves phase. The arc-melted Zr-based alloys exhibited a significant presence of C14 Laves phases and small amounts of NiZr intermetallic phase. Hydrogen storage properties investigated through pressure-composition-temperature (PCT) absorption and desorption isotherms revealed that the Zr33Cr22Mn15Fe25Ni5 alloy could absorb 1.8% (H/M = 1.2) of hydrogen with fast kinetics at room temperature after a simple heat activation, while the Zr33(CrMnFeNi)67 alloy could reversibly absorb 1.6% (H/M = 1) with equally fast kinetics. Zr-rich alloys exhibited a low hydrogen equilibrium pressure in the PCT isotherms. After full hydrogenation at room temperature, the initial metallic C14 Laves phases were converted to the respective Laves phase hydrides in both cases. Under cycling, the fractions of the secondary NiZr and the C14 phase change as the samples become more activated. The microstructural analysis, before and after the cycling, showed a very homogeneous microstructure and good distribution of the elements in both alloys.

Thermodynamic Assessment of the Fe–Mn–Ni System and Diffusion Mobility of Its Face-Centered Cubic Phase

Through extrapolation of updated binary descriptions, the Fe–Mn–Ni system was thermodynamically elucidated in a self-consistent way. The obtained thermodynamic description was confirmed to be reliable by measuring phase equilibria at relatively low temperatures. Our current thermodynamic evaluation can describe the phase stabilities over a wide temperature range and provide a reliable thermodynamic factor for the diffusion mobility optimization. For the face-centered cubic (FCC) phase in the investigated alloy system, optimization of diffusion mobilities was accomplished with the CALPHAD method. Interdiffusivities were extracted based on the composition-distance profiles of diffusion couples investigated herein. Through comprehensive diffusion behavior comparisons, our proposed diffusion mobilities were confirmed.

Thermodynamic modeling of the Al–Cr–Mo–Ni system

The Al–Cr–Mo–Ni system is of technical interest because it is an essential system for the thermodynamic modeling of systems related to the Ni- and NiAl-based superalloys. The knowledge of phase behaviors and thermodynamic properties of this system will be greatly helpful for the development of related alloys. Thermodynamic modeling of the Al–Cr–Mo–Ni system in the previous effort is not satisfactory. In this study, the Cr–Mo–Ni system was re-optimized with more sophisticated binary databases, and a new thermodynamic database of the Al–Cr–Mo–Ni system was established. A satisfactory agreement between calculated results and experimental data was obtained. The thermodynamic database developed in this study is suitable for assisting the design of both Ni- and NiAl-based superalloys.

Electrical resistivity of coatings of quasicrystalline and crystalline phases of the Ti—Zr—Ni system in the temperature range 4–300 K

The temperature dependence of the electrical resistivity in the temperature range from 4.4 to 300 K for Ti41Zr41Ni18 (at. %) thin coatings of different crystal perfection and phase composition was studied. The coatings were deposited by magnetron sputtering with subsequent vacuum annealing in various modes ensuring the formation of several heterophase combinations, which included 1/1 and 2/1 approximation phases, a quasicrystalline icosahedral phase, a Laves phase (Ti, Zr)2Ni, and an α-Ti (Zr) solid solution. The structure before and after annealing was studied by X-ray diffractometry. It was established that coatings with a predominant content of amorphous, quasicrystalline, or approximant 2/1 phases have a temperature coefficient of resistance less than zero, while samples with a predominance of crystalline phases demonstrate characteristic metallic conductivity. The temperature dependence of the electrical resistivity of the Ti41Zr41Ni18 quasicrystalline coating turned out to be similar to the dependence in bulk samples of the Ti40Zr40Ni20 composition. The electrical resistivity of the approximant 2/1 phase with a low content of the additional Laves phase in the film has an almost constant value in the entire investigated temperature range.

Nanosorbent based on coprecipitation of ZnO in goethite for competitive sorption of Cd(II)-Pb(II) and Cd(II)-Pb(II)-Ni(II) systems.

Amongst the various water pollutants, heavy metal ions require special attention because of their toxic nature and effects on humans and the environment. Preserving natural resources will have positive impacts on living conditions by reducing diseases and water treatment by nanotechnology is effective in solving this problem owing to the properties of nanomaterials. In this study, a goethite nanoparticle was prepared by hydrothermal method, while ZnO/goethite nanocomposite by co-precipitation was developed. The nanoparticles were characterized using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transform Electron Microscopy (TEM), Thermogravimetric Differential Thermal Analysis (TGA-DTA), Dynamic Light Scattering (DLS), and Breunner-Emmet-Teller (BET) surface area analysis. The adsorption of Cd(II)-Pb(II) and Cd(II)-Pb(II)-Ni(II) ions systems on ZnO/goethite nanocomposite was investigated in a batch mode. The findings of the study showed that nanoparticles ZnO/goethite composite were mixed of spherical and rod-like shapes. The BET results revealed average particle sizes of 41.11nm for nanoparticles for ZnO/goethite while TGA/DTA confirmed the stability of the adsorbents. The optimum adsorption capacities of the nanocomposite for Pb(II), Cd(II), and Ni(II) ions from the Pb-Cd-Ni ternary system were 415.5, 195.3, and 87.13mgg-1, respectively. The adsorption isotherm data fitted well with the Langmuir isotherm model. The study concluded that the nanoparticle adsorbents are efficient for the remediation of toxic pollutants and are, therefore, recommended for wastewater treatment.

Formation of Films of Alloys of Cr–Ni, Cr–Ni–Si and Fe–Ni Systems by Sublimation and Evaporation Methods for Electronic Products

The processes of formation of films of alloys of the Cr–Ni, Cr–Ni–Si and Fe–Ni systems with a stab le elemental composition by evaporation methods are considered. It is shown that due to the large difference in the melting temperatures of Ni and Cr, nichrome films are obtained by sublimation. The design of the evaporator is proposed, which makes it possible to stabilize the composition of the films. Calculations of azeotropic compositions of alloys of the Cr–Ni–Si system have been carried out. The position of the isobars of the total pressure of iron and nickel on the state diagram was determined during evaporation in vacuum. The azeotropic composition of the alloy of the Fe–Ni system was calculated and experimentally verified.

Atomic Scale Diffusion Study in Quaternary and Quinary Alloys of Co–Cr–Fe–Mn–Ni System

Atomic Scale Diffusion Study in Quaternary and Quinary Alloys of Co–Cr–Fe–Mn–Ni System

Chain‐walking polymerization of ethylene and 1‐octene with ortho‐phenyl‐based α‐diimine Ni (II) catalysts

A class of ortho‐phenyl‐substituted Ni (II) α‐diimine complexes with variable electronic nature in the 4‐phenyl position, {[(4‐Me‐2‐(4‐R‐C6H4)C6H3N=C)2Naphth]NiBr2, R = OMe (C1); R = Me (C2); R = H (C3)}, was prepared and characterized. These nickel dibromide complexes were confirmed by X‐ray crystallography analysis and crystallized as a centrosymmetric bromine‐bridged dimer in a distorted tetrahedral geometry at the two Ni (II) centers connected by a four‐membered ring. Because of the conjugation effect and steric hindrance effect of ortho‐phenyl substituent, these Ni‐Et2AlCl systems via controlled chain‐walking ethylene polymerization performed with high catalytic activities of up to 3.10 × 106 g PE (mol Ni h)−1 to yield high molecular weight branched PEs with narrow Mw/Mn values (PDI ≤ 2.39). This Ni (II) system also conducted the chain‐walking polymerization of 1‐octene, resulting in highly branched polyolefins (up to 107 branches/1000C).

Role of Crystal Orientation, Temperature, and Strain Rate on the Mechanical Characterization of Nickel: An Atomistic-scale investigation

In this article, the influence of crystallographic orientation on the mechanical properties of pristine nickel (Ni) during uniaxial tensile deformation was explored by utilizing molecular dynamics simulations. To study the influence of [0 01] and [11 8 5] crystal orientations on the mechanical properties and microstructural evolution of pristine Ni, simulations were performed at different temperatures ranging from 100 K to 900 K and at strain rates ranging from 10 7 to 10 10 s–1. The results revealed that Ni with [11 8 5] orientation showed a higher elastic modulus than Ni with [0 0 1] orientation, whereas the yield strength of [0 0 1] orientation was higher than [11 8 5] orientation for a combination of temperatures and strain rates. Also, in comparison to [11 8 5] crystal orientation, the system with [0 0 1] orientation showed a high amount of dislocation density at the yield strain point for lower strain rates. At higher strain rates, the face-centered cubic to body-centered cubic transition was more prominent in the Ni system with [0 0 1] orientation, and it tends to decrease with the increase in temperature. Our present work may help materials scientists design materials with different crystal orientations that can perform according to the applied strain rates and temperatures. It is also proposed that tailoring of mechanical properties is achievable by exposing Ni with different crystal orientations to various environmental conditions (cryogenic, ambient, and elevated temperatures with different applied strain rates).

Improving the Long-term Cycle Performance of xLi2MnO3·(1-x)LiMeO2/Li4Ti5O12 Cells via Prelithiation and Electrolyte Engineering

Toward the development of high energy density and long lifetime batteries for behind-the-meter storage (BTMS) applications, Li- and Mn-rich layered oxide cathode (xLi2MnO3·(1-x)LiMeO2, Me = Ni, Mn, and etc., LMR-NM) and Li4Ti5O12 (LTO) anode system was examined. To mitigate the major degradation mechanisms at each electrode (i.e., loss of Li inventory (LLI) at the anode and transition metal dissolution and oxygen release at the cathode), two approaches were taken—prelithiating the LTO electrode and varying the electrolyte solvent compositions. The effect of prelithiation and electrolyte engineering on the long-term cycle performance of LMR-NM/LTO cells were systematically evaluated via electrochemical analyses and post-mortem characterizations. By using a prelithiated LTO anode and supplying additional Li to the system, the capacity retention of LMR-NM/LTO system was improved. The degree of enhancement was dependent on the types of electrolytes used, as their decomposition products determined the level of LLI. With increased capacity retention, however, the cathode was utilized to a greater extent, resulting in more severe loss of the cathode active material. Thus, all degradation mechanisms should be considered comprehensively when designing high performance LMR-NM/LTO cells to account for their complex interplay.

Investigation of the applicability of Cu–Fe–Mn–Ni based high entropy and compositionally complex alloys as metal matrix composites for cobalt free hot-pressed diamond tools

Due to the rising demand and carcinogenic effect of cobalt, alternative metal matrixes need to be developed for hot-pressed diamond tools. Due to this reason High-Entropy alloys without cobalt were calculated via phase fraction diagrams. Three alloys of the Al–Cu–Fe–Mn–Ni system Al30Cu30Fe5Mn25Ni10, Al11.25Cu35Fe5Mn20Ni28.75 and Al5Cu20Fe25Mn25Ni25 were chosen due to their different crystal structures ranging from pure bcc, eutectic fcc-bcc to pure fcc crystal structure. Cr5Cu20Fe25Mn25Ni25 was chosen to verify the change of one element on the consolidation properties. The alloys were mechanically alloyed and hot-pressed at 800 °C for 3 min without and at 900 °C for 3 min with diamonds. Porosity increased with the fraction of bcc solid solution in the investigated alloys of the Al–Cu–Fe–Mn–Ni system. Samples consisting of Cr5Cu20Fe25Mn25Ni25 showed the lowest porosity, which was attributed to precipitation of a second copper-rich fcc solid solution around the remaining pores. At a process temperature of 800 °C and 3 min isothermal hold the samples featured a porosity of only 2.72%. Within the XRD patterns and SEM images of the hot-pressed samples with diamonds no graphitization or formation of carbides could be observed. Therefore, Cr5Cu20Fe25Mn25Ni25 was identified as a promising cobalt free metal-matrix candidate for diamond tools.

Obtaining Multicomponent Coatings of a Stable Composition for Electromagnetic Radiation Screens

The formation processes of coatings of Cu–Ni and Ag–Cu systems with a stable elemental composition by the method of electron-beam evaporation are considered. It is shown that in the zone of action of the electron beam on the ingot placed in the crucible at the total vapor pressure of the alloy elements Σp above the pressure under the cap of the installation, the melt boils, and in the outer zone adjacent to the melt zone, the process of sublimation of the hard alloy occurs. The microrelief and elemental composition of the surface layer of the Cu–Ni alloy ingot in the zones of evaporation and sublimation, as well as the elemental composition of the coatings deposited in this case, have been studied. It is shown that the most acceptable way to obtain coatings of the Cu–Ni system with a stable elemental composition is the simultaneous electron-beam evaporation of copper and nickel from two crucibles. The azeotropic composition of the alloy of the Ag–Cu system was calculated and experimentally verified. The research results are used in the manufacture of multilayered screens of electromagnetic radiation.

Site occupancies in a chemically complex σ-phase from the high-entropy Cr–Mn–Fe–Co–Ni system

Site occupancies in a single-phase σ-intermetallic compound of composition Cr46Mn15.2Fe16.3Co17Ni5.5 (in at.%) were studied. To the best of the authors’ knowledge, such a complex analysis with 5 elements occupying 5 different sites has never been tackled before and is addressed here using cutting edge X-ray diffraction techniques, absorption spectroscopy and simulations. Resonant powder diffraction data were collected at the K-edges of each of the five elements and the site occupancies were refined by a joint Rietveld analysis. Dispersion coefficients were retrieved independently from tabulated values, Kramers-Kronig relations and reference samples. Additional Extended X-ray Absorption Fine Structure (EXAFS) measurements were used to confirm the site occupancies and bond lengths. The site occupancies were independently obtained by a thermodynamic approach based on the enthalpies of formation of the 55 = 3125 configurations generated by the ordered distribution of the five components on the five sublattices, derived from a machine learning approach based on a DFT database. Overall, the calculations and experiments are in excellent agreement and reveal that the σ phase can accommodate a considerable degree of disorder, which consequences for thermodynamic modeling are discussed. The configurational entropy (S) of the σ phase represents 84% of that of a fully disordered alloy with the same composition, which is much larger than that expected for a fully ordered intermetallic phase (S = 0). The corresponding entropic stabilization is one of the reasons for the fact that the σ phase is one of the most important intermetallic that precipitates in high-entropy alloys and many engineering materials.

Design and mechanosynthesis of Low-Weight High-Entropy Alloys with hydrogen storage potential properties

This investigation allows designed MgAl-based Low-Weight High-Entropy Alloys (LWHEAs) with a BCC-type structure, using a MgAlTi(X)Ni system where X = Fe, Cr and Co, with hydrogen storage potential properties. The BBC-type alloys were designed considering empiric thermodynamic parameters and obtained by high-energy ball-milling. The structure, morphology, thermal stability and hydrogen sorption properties were studied. Also, the influence of Valence Electron Concentration (VECmix) and Electronegativity difference (Δχmix) parameters on the hydrogen storage capacity of alloys was evaluated. The formation of the equiatomic MgAlTiFeNi, MgAlTiCrNi and MgAlTiCoNi BCC-type LWHEAs with densities between 4.3 ≤ ρ ≥ 4.6 g cm−3 was obtained at 8 h of milling. Alloyed powders show a homogeneous elemental distribution with heterogeneous particles of different sizes and a surface area of ∼ 2 g cm−2. Under high-temperature conditions, the LWHEAs structure changes from BCC to B2. The MgAlTiCoNi alloy presented a maximum hydrogen storage capacity of 2.1% weight H2 at 473 K and 1 MPa. The hydrogen storage depended on VECmix and Δχmix parameters in LWHEAs with the same mixing Entropy.

Synthesis of branched polyethylene waxes using benzocycloalkyl pyridine-imine Ni(II) catalysts with dibenzosuberyl group

Our previous works revealed that dibenzosuberyl groups can suppress chain transfer reactions in many late-transition metal-catalyzed ethylene polymerization systems. In this study, we synthesized three benzocycloalkyl or naphthyl pyridine-imine Ni(II) complexes with a single o-aryl dibenzosuberyl substituent. The generated Ni(II) complexes exhibited moderate activities (3.6–7.6 × 105 g·mol−1·h–1) and yielded branched (44–69/1000 C) polyethylene waxes with appropriate molecular weights (3.0–9.1 kg/mol) in ethylene polymerization. Moreover, compared to the planar naphthyl Ni(II) complex, the more stereospecific benzocyclohexyl Ni(II) complex produced 2 times higher molecular weight polyethylene. Most importantly, the single o-aryl dibenzosuberyl substituent can significantly suppress chain transfer during polymerization and increase the molecular weight of the polyethylene produced in this pyridine-imine Ni(II) system with respect to the dibenzhydryl substituent. The resulting branched polyethylene waxes with suitable molecular weights can be used as additives in the plastic processing, coating and dyeing industries.

Wagner interaction coefficients of nitrogen with chromium and molibdenum in liquid nickel-based alloys

The authors propose a simple theory of thermodynamic properties of liquid nitrogen solutions in alloys of the Fe – Ni – Cr and Fe – Ni – Mo systems. This theory is analogous to the theory for liquid nitrogen solutions in binary alloys of the Fe – Cr and Fe – Ni systems proposed previously by the authors in 2019 and 2021. The theory is based on lattice model of ternary liquid solutions of the Fe – Ni – Cr and Fe – Ni – Mo systems. The model assumes a FCC lattice. Atoms of Fe, Ni, Cr and Mo are deposed in the sites of the lattice. Nitrogen atoms are located in octahedral interstices. The nitrogen atom interacts only with the metal atoms located in the lattice sites neighboring to it. This interaction is pairwise. It is assumed that the energy of this interaction depends neither on composition nor on temperature. It is supposed that the liquid solutions in the Fe – Ni – Cr and Fe – Ni – Mo systems are perfect. Within the framework of the proposed theory, the relation is obtained that expresses the Wagner interaction coefficient between nitrogen and chromium in liquid nickel-based alloys \(\varepsilon _{\rm{N}}^{{\rm{Cr}}}\)(Ni). The right-hand part of the appropriate formula is a function of the Wagner interaction coefficients between nitrogen and chromium \(\varepsilon _{\rm{N}}^{{\rm{Cr}}}\)(Fe) and between nitrogen and nickel \(\varepsilon _{\rm{N}}^{{\rm{Ni}}}\)(Fe) in liquid iron-based alloys. A similar relation is obtained for the Wagner interaction coefficient between nitrogen and molybdenum in liquid nickel-based alloys \(\varepsilon _{\rm{N}}^{{\rm{Mo}}}\)(Ni). According to the first of these formulas, the value \(\varepsilon _{\rm{N}}^{{\rm{Cr}}}\)(Ni) = –21,9 at a temperature of 1873 K is calculated. This corresponds to the value of the Langenberg interaction coefficient \(e _{\rm{N}}^{{\rm{Cr}}}\)(Ni) = –0,108, which coincides with experimental estimate. According to the second formula, the value \(\varepsilon _{\rm{N}}^{{\rm{Mo}}}\)(Ni) = –14,3 is calculated at a temperature 1873 K. This corresponds to the value of the Langenberg interaction coefficient \(e _{\rm{N}}^{{\rm{Cr}}}\)(Ni) = –0,036, which is in satisfactory agreement with the experimental estimate \(\varepsilon _{\rm{N}}^{{\rm{Mo}}}\)(Ni) = –15,1; \(e _{\rm{N}}^{{\rm{Cr}}}\)(Ni) = –0,038.

Correlation of narrow-band imaging findings using the Ni and European Laryngeal Society classification systems during in-office flexible laryngoscopy with histopathology.

This study used the European Laryngeal Society (2016) and Ni (2011 and 2019) classifications for narrow-band imaging and correlated the findings with histopathology. Retrospective analysis was conducted by retrieving data of patients who underwent micro-laryngoscopy for suspicious glottic lesions. The narrow-band imaging findings were classified using both classification systems. Retrieved histopathology report findings were correlated with narrow-band imaging data. Using the European Laryngeal Society and Ni classifications, 37 (69.8 per cent) and 35 (66 per cent) patients, respectively, were suspected to have malignant lesions. Upon histopathology, 37 (69.8 per cent) lesions were malignant. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy using the European Laryngeal Society classification were 91.9 per cent, 81.3 per cent, 91.9 per cent, 81.3 per cent and 88.7 per cent, and using the Ni classification were 91.9 per cent, 93.8 per cent, 97.1 per cent, 83.3 per cent and 92.5 per cent, respectively. The Ni classification had better specificity and accuracy. The European Laryngeal Society classification is simple to use and may serve as a useful screening tool. For optimum results, both European Laryngeal Society and Ni classifications may be used together, in that order.

Estimating the temperature dependent zero-phase-fraction features in ternary phase diagram via Bayesian approach

A complete ternary phase diagram under constant pressure describes conditions of phase regions in the composition–temperature space, where the zero-phase-fraction (ZPF) features are in the form of point, curve, or surface. In this work, we propose an approach to determine the ZPF features and their uncertainty from the discrete data points on the isothermal sections at different temperatures. Domain knowledge of phase diagrams was used as prior in Bayesian statistics. The schematic and effectiveness of the developed method were demonstrated by two model systems and two actual systems. Besides, an experimentally determined Fe–Co–Ni system has been employed to demonstrate how to determine the phase boundary surfaces of the ternary system with combination of experimental data and information from the sub-binary systems. Phase boundary surfaces of the ternary system can be satisfactorily determined even with the data of only one isothermal section when coupled with the information from the sub-binary systems.

Hydrogen Production from Gadolinium-Promoted Yttrium-Zirconium-Supported Ni Catalysts through Dry Methane Reforming.

Hydrogen production from dry reforming of methane (DRM) not only concerns with green energy but also involves the consumption of two greenhouse gases CH4 and CO2. The lattice oxygen endowing capacity, thermostability, and efficient anchoring of Ni has brought the attention of the DRM community over the yttria-zirconia-supported Ni system (Ni/Y + Zr). Herein, Gd-promoted Ni/Y + Zr is characterized and investigated for hydrogen production through DRM. The H2-TPR → CO2-TPD → H2-TPR cyclic experiment indicates that most of the catalytic active site (Ni) remains present during the DRM reaction over all catalyst systems. Upon Y addition, the tetragonal zirconia-yttrium oxide phase stabilizes the support. Gadolinium promotional addition up to 4 wt % modifies the surface by formation of the cubic zirconium gadolinium oxide phase, limits the size of NiO, and makes reducible NiO moderately interacted species available over the catalyst surface and resists coke deposition. The 5Ni4Gd/Y + Zr catalyst shows about ∼80% yield of hydrogen constantly up to 24 h at 800 °C.