Ni Content Research Articles

F-doped Co-free LiNixMn1-xO2 (0.7 ≤ x ≤ 0.9) cathodes for ameliorating electrochemical performance of Li-ion batteries

Ni-rich LiNiCoMnO2 cathodes, which exhibit high energy densities and layered structures, have been studied For Li-ion batteries (LIBs) with high capacities and excellent stabilities. However, the high cost and price fluctuation of Co as the main element in the cathodes remain severe issues for the stable development of LIBs. Therefore, in this study, F-doped Co-free Ni-rich LiNixMn1-xO2 (0.7 ≤ x ≤ 0.9) cathodes were prepared for high-performance LIBs. With increasing Ni content, the undoped Ni-rich LiNixMn1-xO2 cathodes exhibited increased discharge capacities and decreased stabilities. In contrast, the F-doped Ni-rich LiNixMn1-xO2 cathodes delivered higher cycle retentions at 0.5 C for 100 cycles compared to the undoped cathodes. In addition, the F doping of Ni-rich LiNixMn1-xO2 cathodes can facilitate Li-ion diffusion, retaining their reversibility and high capacities at high current densities.

Microstructure and mechanical properties of Ti2Ni alloy fabricated by direct energy deposition

It is difficult to prepare Ti2Ni alloys using traditional single-wire arc additive manufacturing. In this study, a Ti2Ni alloy wall was fabricated in situ by double-wire arc additive manufacturing with pure Ti and Ni wires, and the resulting material has the potential to be applied to spacecraft and ground armor protection. In the stable region, the Ti: Ni content ratio was close to 2:1 after stabilization, indicating that the as-built wall was very close to the designed composition (Ti2Ni). From the top of the wall to the substrate, the microstructure evolved as follows: Ti2Ni + NiTi → Ti2Ni + NiTi + α-Ti → α-Ti + Ti2Ni. In the stable region, the hardness remained stable at approximately 660 HV0.5.

Investigation of the influence of Al layer and total film thicknesses on structural and related magnetic properties in sputtered Ni/Al multilayer thin films

The effects of parameters of Al layer thickness and total film thickness on the structural and related magnetic properties of Ni/Al multilayer films were investigated. The films were deposited by a dual sputtering. The Ni content decreased gradually while the Al content increased as the Al layer thickness increased. It was also observed that the total film thickness had little effect on the film content. All films have a face-centred cubic structure. And, the surface morphology of Ni/Al films is more uniform and homogeneous than the surface of Ni film. For magnetic analysis, the properties were strongly changed with the parameters. The saturation magnetisation, Ms of Ni film was obtained as 572 emu/cm3 while the Ms of the Ni/Al films decreased from 441 to 298 emu/cm3 with increasing Al content in the films caused by the Al layer thickness. And, the increase of total film thickness resulted in a decrease of Ms value. While the coercivity, Hc value of the Ni film was 90 Oe, Hc of Ni/Al films was decreased to ~ 39 Oe with the formation of multilayer structure. Ni/Al multilayers were obtained magnetically softer than the Ni film. The Ms and Hc values were significantly affected by the variation of the film content and crystal structure caused by the changes in deposition parameters. Therefore, this is a fundamental step for Ni/Al multilayers to improve the properties of these films for their potential applications in microelectronic devices.

The influence of electrodeposition potential on the chemical composition, structure and magnetic properties of FeCoNi nanowires

FeCoNi alloyed nanowires with diameters of 40 nm and 100 nm and a length of 6 µm were electrodeposited in the polycarbonate membranes at constant cathodic potentials ranging from −1.0 to −1.8 V. The increase in cathodic potential caused an increase in Ni content with a simultaneous decrease in Fe and Co concentrations. The samples showed an fcc structure (with a small hcp fraction observed in one sample) with a preferred growth along [111] direction, which changed to a [220] texture at higher deposition potentials. With the increase in Ni content, a shortening of the lattice parameters and an increase in the crystallite size were observed. Various chemical compositions resulted in the modification of the magnetic properties of nanowires. The magnetization saturation value increased with increasing cathodic potential for both types of nanowires. However, coercivity and squareness rose for samples with a diameter of 40 nm and fell down for 100 nm diameter nanowires. This specific behavior was explained based on dipolar interactions, which can be neglected in 40 nm diameter nanowires, due to the low membrane porosity.

Eco-friendly approach to decrease the harmful effects of untreated wastewater on growth, yield, biochemical constituents, and heavy metal contents of carrot (Daucus carota L.).

Here, the impact of irrigation using untreated wastewater (WW) on carrots (Daucus carota L.) was examined. We hypothesized that the addition of ethylenediaminetetraacetic acid (EDTA), dry algal powder (Spirulina platensis or Chlorella vulgaris), and Salix alba leaves powder would function as chelators for harmful contaminants in wastewater. The findings showed that irrigation of carrot plants with the sampled untreated wastewater led to significant decreases in the shoot lengths, fresh, dry weights of shoots and roots at stage I, the diameter of roots, pigment content, carotenoids, total soluble carbohydrate content, and soluble protein content. Furthermore, a significantly increased level of proline, total phenols, and the activities of polyphenol oxidase (PPO), peroxidase (POX), superoxide dismutase (SOD), and catalase (CAT) was identified in stage I samples. In contrast to the stage I, the length of the roots, the number of leaves on each plant, wet and dry weights of the stage II roots were all greatly enhanced. In spite of the increased yield due to the wastewater irrigation, carrot roots irrigated with wastewater had significantly more cadmium (Cd), nickel (Ni), cobalt (Co), and lead (Pb) than is considered safe. Our data clearly show that the application of Spirulina platensis, Chlorella vulgaris, EDTA, and leaves powder of salix was able to alleviate the toxicity of wastewater on carrot plants. For example, we recorded a significant decrease in the accumulation of carrot's Cd, Ni, Co, and Pb contents. We conclude that the treatments with Spirulina platensis and Chlorella vulgaris can be utilized as eco-friendly tools to lessen the damaging effects of wastewater irrigation on carrot plants.

Well-Adhered Ti Alloying Layer on NiTi Alloy: Surface Ni Content, Corrosion Resistance, and Cytocompatibility

Well-Adhered Ti Alloying Layer on NiTi Alloy: Surface Ni Content, Corrosion Resistance, and Cytocompatibility

Low-Electronegativity Cationic High-Entropy Doping to Trigger Stable Anion Redox Activity for High-Ni Co-Free Layered Cathodes in Li-Ion Batteries.

LiNi0.8 Co0.1 Mn0.1 O2 (NCM-811) exhibits the highest capacity in commercial lithium-ion batteries (LIBs), and the high Ni content (80 %) provides the only route for high energy density. However, the cationic structure instability arisen from the increase of Ni content (>80 %) limits the further increase of the capacity, and inevitable O2 release related to anionic structure instability hinders the utilization of anion redox activity. Here, by comparing various combinations of high-entropy dopants substituted Co element, we propose a low-electronegativity cationic high-entropy doping strategy to fabricate the high-Ni Co-free layered cathode (LiNi0.8 Mn0.12 Al0.02 Ti0.02 Cr0.02 Fe0.02 O2 ) that exhibits much higher capacity and cycling stability. Configurational disorder originated from cationic high-entropy doping in transition metal (TM) layer, anchors the oxidized lattice oxygen ((O2 )n- ) to preserve high (O2 )n- content, triggering the anion redox activity. Electron transfer induced by applying TM dopants with lower electronegativity than that of Co element, increases the electron density of O in TM-O octahedron (TM-O6 ) configuration to reach higher (O2 )n- content, resulting in the higher anion redox activity. With exploring the stabilization effect on both cations and anions of high-entropy doping and low-electronegativity cationic modified anion redox activity, we propose an innovative and variable pathway for rationally tuning the properties of commercial cathodes.

Low‐Electronegativity Cationic High‐Entropy Doping to Trigger Stable Anion Redox Activity for High‐Ni Co‐Free Layered Cathodes in Li‐Ion Batteries

AbstractLiNi0.8Co0.1Mn0.1O2 (NCM‐811) exhibits the highest capacity in commercial lithium‐ion batteries (LIBs), and the high Ni content (80 %) provides the only route for high energy density. However, the cationic structure instability arisen from the increase of Ni content (>80 %) limits the further increase of the capacity, and inevitable O2 release related to anionic structure instability hinders the utilization of anion redox activity. Here, by comparing various combinations of high‐entropy dopants substituted Co element, we propose a low‐electronegativity cationic high‐entropy doping strategy to fabricate the high‐Ni Co‐free layered cathode (LiNi0.8Mn0.12Al0.02Ti0.02Cr0.02Fe0.02O2) that exhibits much higher capacity and cycling stability. Configurational disorder originated from cationic high‐entropy doping in transition metal (TM) layer, anchors the oxidized lattice oxygen ((O2)n−) to preserve high (O2)n− content, triggering the anion redox activity. Electron transfer induced by applying TM dopants with lower electronegativity than that of Co element, increases the electron density of O in TM‐O octahedron (TM‐O6) configuration to reach higher (O2)n− content, resulting in the higher anion redox activity. With exploring the stabilization effect on both cations and anions of high‐entropy doping and low‐electronegativity cationic modified anion redox activity, we propose an innovative and variable pathway for rationally tuning the properties of commercial cathodes.

Ni‐Alloyed Copper Iodide Thin Films: Microstructural Features and Functional Performance

To tailor electrical properties of often degenerate pristine CuI, Ni is introduced as alloy constituent. Cosputtering in a reactive, but also in an inert atmosphere as well as pulsed laser deposition (PLD), is used to grow thin films. The Ni content within the alloy thin films is systematically varied for different growth techniques and growth conditions. A solubility limit is evidenced by an additional phase for Ni contents , observed in X‐Ray diffraction and atomic force microscopy by a change in surface morphology. Furthermore, metallic, nanoscaled nickel clusters, revealed by X‐Ray photoelectron spectroscopy and high‐resolution transmission electron microscopy (HRTEM), underpin a solubility limit of Ni in CuI. Although no reduction of charge carrier density is observed with increasing Ni content, a dilute magnetic behavior of the thin films is observed in vibrating sample magnetometry. Further, independent of the deposition technique, unique multilayer features are observed in HRTEM measurements for thin films of a cation composition of . Opposite to previous claims, no transition to n‐type behavior was observed, which was also confirmed by density functional theory calculations of the alloy system.

Microstructure and anti-oxidation behavior of laser clad Ni[sbnd]Si coating on molybdenum surface

Ni-Si alloy coatings with various compositions were fabricated on molybdenum surfaces using laser cladding technology. The sound metallurgical bond without cracks and pores between coatings and substrat was revealed.The microstructure and phase composition of the coatings were analyzed using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The oxidation resistance of the coatings was investigated in a static air environment at 700 °C. The results reveal that the coatings primarily consist of a γ-Ni solid solution, Ni3Si phase, and Mo2Ni3Si phase. Furthermore, the Mo2Ni3Si phase content increases with decreasing Ni content in the powder ratio. The oxidation kinetics curve of the NiSi alloy coatings follows a parabolic law. The oxide layer formed on the coating surface is uniform and dense, comprising SiO2, MoO3, and NiMoO4. Based on the comprehensive analysis of the microstructure of the oxide layer, the Ni90Si10 coating demonstrated superior oxidation resistance

An atomistic study of effects of temperature and Ni element on the phase transition and wear behavior of NiTi shape memory alloy

Phase transition and tribological behavior of NiTi alloys have drawn great attention. Molecular dynamics simulation was adopted to investigate the effects of temperature on the mechanical behavior and variant formation of NiTi, as well as its wear behavior. Thermally and stress-induced phase transition behavior of NiTi alloys were studied. It is found that residual austenite phase boundaries during martensitic phase transformation could inhibit martensitic phase transition, changing the phase transition temperatures, and the mechanical properties of NiTi. Wear behavior of single-crystal NiTi with a wide temperature domain and content was studied. The optimal wear resistance of NiTi was at 300 K during cooling. Appropriate improvement in Ni content is beneficial to the formation of martensite variants and enhancement of the wear resistance.

Effects of Al3Ni compound on localized plastic deformation and creep strain of Al/Si hypoeutectic material

The mechanical resistance of AS10/xNi hypoeutectic alloy with (x = 0.05% and 0.1%) has been investigated. Vickers hardness (HV) was determined for the samples before and after sintering. All samples were subjected to a compressive creep test at a constant temperature of 298 K and a constant load of 45 MPa. Creep parameters, such as creep rate, sensitivity (m), time exponent (n), β, and ɣ have been calculated and related to the Ni content. Microstructure investigation was conducted using the scanning electron microscope technique (SEMT). After sintering, the results showed that there was a significant improvement in the hardness with the addition of nickel. There is an increase in creep resistance as a result of the distribution of Al3Ni chemical compound across grain boundaries, which stops additional dislocation movement and hence reduces the creep rate.

Factors influencing the martensitic transformation in Ni–Mn–Z (Z = Ga, Sn) Heusler alloys

The martensitic transition temperature of the Ni–Mn–Z (Z = Ga, In, Sn or Sb) generally scales with the average valence electron per atom ( e/a ) ratio. The e/a ratio can be increased either by increasing Ni content in lieu of Mn or Z (Ni-rich) or by substituting Mn for Z (Mn-rich). While the Mn-rich alloys display the expected scaling behaviour of the martensitic transition temperature, the Ni-rich alloys, with the exception of Z = Ga alloys, do not exhibit any dependency on the e/a ratio. By carefully studying and comparing the structure, local structure and the physical properties of the Ni-rich and Mn-rich Ni–Mn–Ga and Ni–Mn–Sn alloys, the cause of the difference in behaviour is identified. The off-stoichiometry brought about by increasing the Ni or Mn content, results in the formation of a new local structural environment in addition to the Heusler-like environment. If either of the two local structural environments is martensitic, then the resulting Ni-rich or Mn-rich alloy also exhibits martensitic transformation.

Textures and trace element geochemistry of pyrite in Gaoloushan ore section of the Yangshan gold belt, West Qinling: Implications for ore genesis

The Devonian Sanhekou Group phyllite in the Yangshan gold belt includes multiple stages of pyrite development, and Au is mainly distributed within the pyrite. Bodies within the Gaoloushan ore section of the gold belt are located in the broken and altered carbonaceous phyllite and granitic rock dykes, where quartz vein-type gold ores are more common as compared to other ore sections (Anba, Getiaowan). Studying the trace element distribution characteristics of gold-bearing and non-gold-bearing pyrite can constrain the evolution of ore-forming fluids and the types of ore deposit genesis. Based on detailed fieldwork and microscopic identification, 48 pyrite samples from the 69th exploration line of the Gaoloushan ore section were analyzed in situ by LA-ICP-MS. The following conclusions were drawn: (1) The gold-bearing pyrite formed during the ore-forming stage while the non-gold-bearing pyrite formed during the sedimentary and metamorphic period. The morphology of the pyrites differs, with gold-bearing pyrite mainly characterized by medium-fine grains, impregnation, fine veins, and reticulate structure, with crystal morphology mainly pentagonal dodecahedra or pentagonal octahedra, whereas non-gold-bearing pyrite is mainly characterized by a medium or medium-coarse grains, with stellate, strawberry, or cluster structures, and crystal morphology mainly in the form of cubes or pentagonal octahedra; (2) The As and Te content of the sedimentary pyrite is low, locally below the detection limit, and the Co and Ni contents and ratios vary greatly, with a distribution of 117–945 ppm and ratio distribution of 0.11–1.92. Pyrite from the ore-forming stage is primarily characterized by high As, Pb, Co, Ni, Cu, Sb, Zn, and Se concentrations, with Bi, Au, and trace amounts of Tl, Te, and Sn observed in later formations; (3) Au and As are positively correlated. The average Au content of 60.53 ppm in pyrite from granite dykes is higher than the average Au 15.97 ppm in carbonaceous phyllite. Pyrite particles with Au contents below the detection limit are sourced in carbonaceous phyllite. In addition, the higher As enrichment is observed in pyrite from granite dykes, averaging 35 770.60 ppm with a maximum value of 72 930.19 ppm. In comparison, the average As content in carbonaceous phyllite is 8974.66 ppm, with a maximum of 69 800.50 ppm, and the Au-As diagram indicates that gold in the Gaoloushan ore section is mainly in the form of solid solution gold within the pyrite lattice; (4) Statistical analysis of the Co/Ni ratio variation in the different lithologies and pyrite stages reveals an initial increase followed by a decrease. The median Co/Ni ratio variations during the mineralization stages of Py1s (0.51–0.7), Py1m (1.35–2.25), Py2 (1.43–1.87), Py1-2 m (1.53), Py2a (1.59), Py2b (1.4), Py2s (1.2), Py2m (1.63), and Py3 (0.19–1.40) suggest that magmatic-hydrothermal fluids dominated during the early stage of mineralization in the gold belt and metamorphic fluids during the main mineralization stage, with deep-seated metamorphic fluids playing a significant role in the late mineralization stage. The varying proportions of ore-forming fluids are likely to have been crucial in controlling gold mineralization in the Yangshan gold belt.

Surface reconstruction of La0.6Sr0.4Co0.8Ni0.2O3-δ perovskite nanofibers for oxygen evolution reaction

Perovskites have become promising alternatives to precious metal-catalyzed oxygen evolution reaction (OER). Herein, we report the synthesis of several perovskite nanofibers, specifically La0.6Sr0.4CoxNi1-xO3-δ (LSCN), and investigate their electrocatalytic water oxidation activity in alkaline electrolytes. La0.6Sr0.4Co0.8Ni0.2O3-δ (LSCN-0.8) is selected and immersed in an aqueous NaBH4 solution for 1 h for surface reconstruction. The perovskite nanofibers' electrocatalytic OER activity and stability are rigorously evaluated using a standard three-electrode system. Results reveal that even a slight Co substitution for Ni content within the LSCN perovskite structure has a notable impact on electrocatalytic activity. Moreover, LSCN-0.8 exhibits an overpotential of 363 mV at 20 mA cm−2 in 1 M KOH. However, significant improvement is observed after the surface reconstruction process. The optimized LSCN-0.8 (now called LSCN-2) displays the lowest OER overpotential (320 mV) under the same conditions. Furthermore, the LSCN-2 nanostructure demonstrates exceptional electrode stability, as evidenced by only a slight decrease in electrocatalytic performance during 5000 cycles of linear sweep voltammetry.

Effects of Ni content on microstructure and fracture toughness of the ZrN/TiNiN nano-multilayer films

ZrN and TiNiN nanolayers are alternately deposited on silicon substrate by magnetron sputtering. A series of ZrN/TiNiN nano-multilayer films with different Ni contents are prepared by varying the Ni:Ti volume ratio of the targets. The effects of Ni content on the microstructures and mechanical properties of ZrN/TiNiN nano-multilayer films are studied by X-ray diffractometer (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and nanoindentation instrument. The results show that with the increase of Ni content, the crystallization degree of ZrN phase first increases and then decreases. Besides, the hardness, elastic modulus and toughness of the films also increase first and then decrease with Ni content increasing. When Ni:Ti= 1:24, the ZrN/TiNiN nano-multilayer films obtain the highest hardness, elastic modulus and fracture toughness, which are 23.2 GPa, 317.8 GPa and 2.29 MPa·m1/2, respectively. This is mainly attributed to the best columnar crystal growth of the ZrN/TiNiN nano-multilayer film. The TiNiN layer changes into face centered cubic structure under the template of ZrN layer, and grows in coherent epitaxy with ZrN layer.

Tailoring the nanotwin spacing of Ni-Mo-W alloys via composition and substrate temperature control

Alloy chemistry and deposition conditions can strongly influence the structure and properties of nanostructured materials. However, in Ni-Mo-W alloys, the limited influence of deposition rate on the twin spacing compels the exploration of other routes to tailor the structure and properties. This study was undertaken to investigate the effect of composition and substrate temperature on the nanotwin spacing of sputter-deposited Ni-Mo-W alloys. Increasing the Ni content from 84 at.% to 93 at.% doubled the average twin spacing from 1.8 nm to 3.8 nm, while raising the substrate temperature from room temperature to 200°C for a fixed Ni content of 91 at.% resulted in an increase from 2.9 nm to 5.0 nm. Concurrent weakening of the {111} texture occurred with both increased Ni and temperature. The combined effectiveness of composition and temperature demonstrated here provides a potential process window for tuning the twin spacing while maintaining the strongly textured columnar structure.

Characteristics and evaluation of heavy metal pollution in a soil–wheat system of an arid oasis city in northwest China

In this paper, the Cu and Ni accumulation and contamination levels in agricultural soils and wheat around a smelter in Jinchang City in northwest China were investigated with a combination of field investigations and indoor analytical tests, using a soil–wheat system as the study area. The average Cu and Ni contents in the soil were 119.50 mg kg–1 and 123.40 mg kg–1, respectively, both of which exceeded the local soil background values. The Cu and Ni contents in 46.15% o and 26.92% of sampling sites, respectively, exceeded the screening values for soil contamination risk in agricultural land in China. The average Cu content in different parts of wheat was in the order of roots (24.22 mg kg–1) > leaves (20.11 mg kg–1) > husks (5.51 mg kg–1) > grains (4.05 mg kg–1) > stalks (3.74 mg kg–1). Furthermore, the average Ni content ranked as leaves (24.64 mg kg–1) > roots (21.12 mg kg–1) > husks (6.95 mg kg–1) > stalks (1.75 mg kg–1) > grains (0.38 mg kg–1). The health risk evaluation showed that with average hazard index values of 0.88 for adults and 1.04 for children for Cu and Ni in wheat grain, wheat in this region is unlikely to pose a health risk to adults but may pose a lesser health risk to children. The Ni bio–concentration and translocation factors in the husk and leaves of wheat were greater than those of Cu and smaller than those of Cu in the other parts of wheat. The results of this study provide basic data for the remediation of heavy metal contamination in local agricultural soils.

Melt infiltration for the preparation of finely dispersed Ni-FeOx nanoparticles on SBA-15 for the hydrodeoxygenation of m-cresol

The polymer-assisted melting infiltration method was used to finely disperse Ni, Fe and bimetallic Ni-Fe precursors in ordered mesoporous SBA-15 support. This approach allowed to obtain small Ni nanoparticles, in the order of 2 nm in size, with finely dispersed iron oxide surrounding metallic Ni, without evidence of Ni-Fe alloy formation. The catalysts were used in the HDO reaction of m-cresol at 300 °C and atmospheric pressure. The conversion of m-cresol was found to be dependent on Ni content, with the total reaction rate decreasing when Ni is partially replaced by iron. Toluene was the main product obtained for both, mono Ni and bimetallic Ni-Fe catalysts, thus suggesting that nickel nanoparticles when in the form of small sized particles, are the active sites for deoxygenation, independent on the presence of oxophilic iron site in their proximity. Such findings will serve for the further design of effective catalysts for the upgrading of lignin-derived bio-oil.

Effect of different feedstocks on the microstructure and mechanical properties of HSLA steel repaired by underwater laser direct metal deposition

Underwater laser direct metal deposition (UDMD) technique shows great potential for the on-site repair of damaged structures in the ocean. In this study, aiming at the possibility of flexible feedstock substitution, two powders with different properties are employed to repair the preprepared HSLA steel plates using UDMD. The combined effects of alloy compositions and UDMD processing on the repair performance including microstructure, mechanical properties and corrosion behavior, are systematically studied. The results show that the localized laser melting/solidification and rapid underwater cooling effect significantly increase the cooling rates, and thus lead to the formation of fine-grained lath martensite and acicular ferrite. The high Ni content in the sample repaired with ultra-high strength (UHS) powder contributes to the interlath austenite. Compared with that of the sample repaired with high strength (HS) powder, the microhardness of the sample repaired with UHS powder is high due to the solid solution strengthening and grain boundary strengthening. In addition, the tensile properties of the UDMD samples exceed the marine steel requirement (yield strength ≥690 MPa). The acceptable impact toughness of the UDMD samples is due to the existence of acicular structures and high fraction HAGBs. Furthermore, the UDMD samples present a better corrosion resistance in comparison with the substrate. The experimental findings demonstrate the employment feasibility of powder substitution on the UDMD repair of complex steel structures in the ocean.