Nickel Oxygen Research Articles

Impact of the clusterization on the solubility of oxygen and vacancy concentration in nickel: A multi-scale approach

Combining thermodynamic concepts with first-principles calculations, we study the solubility of oxygen atoms (O) in nickel. In our approach, we include the possible formation of oxygen clusters (On) and vacancies-oxygens clusters (VOn and V2On). We show that the vacancy-oxygens interactions are strong (approximately 1 eV) and would induce a large concentration of clusters in fcc-Ni. The use of a thermodynamic model, within a grand canonical approach, allows calculation of the vacancy concentration, including these VOn clusters, as a function of O concentration, for different temperatures. We find that at low temperatures (below 600 K), a small content of oxygen (in appm) strongly modifies the vacancy concentration, increasing the total vacancy concentration in the metal by many orders of magnitude more than the thermal vacancy concentration. The vacancy concentration is thus directly controlled by the oxygen content in the metal. At high temperatures, the effect is reduced, becoming negligible near the melting point. These results show the strong impact of interstitial atoms on the vacancy concentration. The influence of the vacancy formation energy is also discussed.

Rapid Hydrogen and Oxygen Atom Transfer by a High-Valent Nickel–Oxygen Species

Terminal high-valent metal-oxygen species are key reaction intermediates in the catalytic cycle of both enzymes (e.g., oxygenases) and synthetic oxidation catalysts. While tremendous efforts have been directed toward the characterization of the biologically relevant terminal manganese-oxygen and iron-oxygen species, the corresponding analogues based on late-transition metals such as cobalt, nickel or copper are relatively scarce. This scarcity is in part related to the "Oxo Wall" concept, which predicts that late transition metals cannot support a terminal oxido ligand in a tetragonal environment. Here, the nickel(II) complex (1) of the tetradentate macrocyclic ligand bearing a 2,6-pyridinedicarboxamidate unit is shown to be an effective catalyst in the chlorination and oxidation of C-H bonds with sodium hypochlorite as terminal oxidant in the presence of acetic acid (AcOH). Insight into the active species responsible for the observed reactivity was gained through the study of the reaction of 1 with ClO- at low temperature by UV-vis absorption, resonance Raman, EPR, ESI-MS, and XAS analyses. DFT calculations aided the assignment of the trapped chromophoric species (3) as a nickel-hypochlorite species. Despite the fact that the formal oxidation state of the nickel in 3 is +4, experimental and computational analysis indicate that 3 is best formulated as a NiIII complex with one unpaired electron delocalized in the ligands surrounding the metal center. Most remarkably, 3 reacts rapidly with a range of substrates including those with strong aliphatic C-H bonds, indicating the direct involvement of 3 in the oxidation/chlorination reactions observed in the 1/ClO-/AcOH catalytic system.

Stability of vacancy-oxygen complexes in bulk nickel: Atomistic and ab initio calculations

This work is concerned with the interactions of multiple oxygen atoms with vacancy clusters Vm of size m in bulk nickel. The calculations were carried out using molecular statics, employing a reactive potential developed recently for the NiO system containing vacancies. In particular, segregation of oxygen inside a mono- and a divacancy are considered for the first time, to complete earlier work on the subject. Overall, we find strong attractive interactions between the oxygen atoms and the vacancy clusters. We argue that this leads to increasing dramatically the solubility of oxygen in nickel. Regarding the complexes VmO1, the results indicate that atomic oxygen inside the vacancy clusters is more stable than at the conventional interstitial sites of the perfect Ni system. This stability is further enhanced as the size of the cavity increases. We have found that a monovacancy (V1) and a divacancy (V2) can trap up to 14 and 22 oxygen atoms, respectively. We have also carried out ab initio calculations, for the purposes of both comparison and validation of the potential used in the current work. We find a very good qualitative agreement between the ab initio results and the predictions obtained from the reactive potential. Both agree well with the experimentally observed facts establishing the influence of point defects on the oxidation processes observed in nickel and its alloys.

Spectroscopically Characterized Synthetic Mononuclear Nickel-Oxygen Species.

Iron, copper, and manganese are the predominant metals found in oxygenases that perform efficient and selective hydrocarbon oxidations and for this reason, a large number of the corresponding metal-oxygen species has been described. However, in recent years nickel has been found in the active site of enzymes involved in oxidation processes, in which nickel-dioxygen species are proposed to play a key role. Owing to this biological relevance and to the existence of different catalytic protocols that involve the use of nickel catalysts in oxidation reactions, there is a growing interest in the detection and characterization of nickel-oxygen species relevant to these processes. In this Minireview the spectroscopically/structurally characterized synthetic superoxo, peroxo, and oxonickel species that have been reported to date are described. From these studies it becomes clear that nickel is a very promising metal in the field of oxidation chemistry with still unexplored possibilities.

Oxygen solubility in liquid nickel containing zirconium

The solubility of oxygen in liquid nickel containing zirconium at 1873 K has been experimentally studied for the first time. It has been shown that zirconium is a rather strong deoxidizing agent in liquid nickel. The equilibrium constant of the reaction of zirconium and oxygen dissolved in liquid nickel (logK(1)(Ni) =–6.788), the interaction parameters characterizing these solutions (eZr(Ni)O =–2.01; eO(Ni)Zr =–0.35; eZr(Ni)Zr = 0.24), and the activity coefficient of zirconium in nickel at infinite dilution (γZr(Ni)o = 1.03 × 10–8) have been determined. The zirconium content at the minimum of the oxygen solubility curve and the corresponding oxygen concentration have been determined.

THERMODYNAMICS OF OXYGEN SOLUTIONS IN THE Fe – Ni, Fe – Co AND Ni – Co MELTS

Thermodynamic analysis of oxygen solutions in the Fe – Ni – O, Fe – Co – O, Co – Ni – O melts was determined. Composition of the oxide phase and the value of the equilibrium oxygen concentration in the melt of those systems were fi rst time obtained in a whole range of alloy compositions. In Fe – Ni – O and Fe – Co – O systems with increasing content of nickel and cobalt in the melts the oxide phase contains mainly FeO in a suffi ciently wide range of content of nickel and cobalt. Only when the mole fraction of nickel is close to unity and the mole fraction of cobalt is more than 0.8, content of NiO and CoO increases sharply. Oxide phase of Co – Ni – O system contains CoO and NiO in the entire range of alloy compositions. In the Fe – Ni and Fe – Co systems nickel and cobalt additives in the melt lead to decreased solubility of oxygen due to the attenuation, both nickel and cobalt, oxygen bonds in the melt and thus increases its activity. Further, by increasing the content of nickel and cobalt, the oxygen concentration in the melt increases slowly at fi rst and then quite rapidly. In Co – Ni system nickel additives to cobalt lead to increasing solubility of oxygen in the whole range of alloy compositions due to a substantially greater solubility of oxygen in nickel than in cobalt.

Thermodynamics of oxygen solutions in Fe-Ni, Fe-Co, and Co-Ni melts

By thermodynamic analysis of oxygen solutions in Fe-Ni-O, Fe-Co-O, and Co-Ni-O melts, the composition of the oxide phase is established for the first time. In addition, the equilibrium oxygen concentrations in these melts are determined over the whole range of alloy compositions. In Fe-Ni-O and Fe-Co-O melts, the oxide phase mainly contains FeO over a relatively broad of alloy compositions. Sharp increase in NiO content is only observed when the molar fraction of nickel exceeds one; sharp increase in CoO content is only observed when the molar fraction of cobalt exceeds 0.8. In the Co-Ni-O system, the oxide phase contains both CoO and NiO over the whole range of alloy compositions. In the Fe-Ni system, adding nickel to the melt reduces the solubility of oxygen as a result of weakening of the oxygen bonds in the melt by nickel and consequent increase in oxygen’s activity. With further increase in nickel content in the melt, the oxygen content rises at first slowly and then very sharply. In the Fe-Co system, analogously, adding cobalt to the melt reduces the solubility of oxygen as a result of weakening of the oxygen bonds in the melt and consequent increase in oxygen’s activity. With further increase in cobalt content, the oxygen content rises at first slowly and then relatively rapidly. In the Co-Ni system, adding nickel to cobalt increases the solubility of oxygen over the whole range of alloy compositions, on account of the significantly greater solubility of oxygen in nickel than in cobalt.

Molecular dynamics simulations of the effects of vacancies on nickel self-diffusion, oxygen diffusion and oxidation initiation in nickel, using the ReaxFF reactive force field

A ReaxFF reactive force field was developed for the nickel–oxygen system. The quantum mechanical (QM) data used to derive the force field parameters included the equations of state of various phases of nickel and that of nickel oxide (NiO), the vacancy formation energy and the vacancy-mediated self-diffusion barrier in the face-centered cubic nickel. Furthermore, in order to study the interstitial diffusion of oxygen atoms in the nickel matrix, the oxygen insertion energies and the diffusion barriers were included in the training set. The force field was validated by performing molecular dynamics (MD) simulations of self-diffusion of nickel and the interstitial diffusion of oxygen. The predicted diffusivity and the activation energy achieved quantitative agreement with their respective published values. Furthermore, this force field enables study of the effects of vacancies on the diffusion of dissolved oxygen and the successive initiation of internal oxidation. A new oxygen diffusion mechanism is proposed in which the oxygen atom diffuses via the movement of the oxygen–vacancy pair. In addition, the MD simulation results suggest that the voids at the grain boundaries can induce local oxygen segregation due to the strong oxygen–vacancy binding effect, which is responsible for the formation of a nickel oxide particle in the void. These results demonstrate that the ReaxFF MD study can contribute to bridging the gap between the QM calculations and the experimental observations in the study of metal oxidation.

Preparation of electroactive modified electrodes based on carbonized paper

The possibilities of application of carbonized paper (CP) for preparation of carbon-containing material modified with various electroactive compounds and composites both in the acidic and alkaline media are studied. It is shown that carbonized paper is an adequate substrate for the electrochemical synthesis of poly-o-phenylenediamine electroactive polymer, nickel oxygen compounds from nickel sulfonated phthalocyanine (NiTsPc), as well as for the chemisorption of silicododecamolybdic acid (SiMo). It is shown that CP modified with nickel compounds can be used as the catalyst for the electrooxidation of ethylene glycol (EG).

First-principles studies on vacancy-modified interstitial diffusion mechanism of oxygen in nickel, associated with large-scale atomic simulation techniques

This paper is concerned with the prediction of oxygen diffusivities in fcc nickel from first-principles calculations and large-scale atomic simulations. Considering only the interstitial octahedral to tetrahedral to octahedral minimum energy pathway for oxygen diffusion in fcc lattice, greatly underestimates the migration barrier and overestimates the diffusivities by several orders of magnitude. The results indicate that vacancies in the Ni-lattice significantly impact the migration barrier of oxygen in nickel. Incorporation of the effect of vacancies results in predicted diffusivities consistent with available experimental data. First-principles calculations show that at high temperatures the vacancy concentration is comparable to the oxygen solubility, and there is a strong binding energy and a redistribution of charge density between the oxygen atom and vacancy. Consequently, there is a strong attraction between the oxygen and vacancy in the Ni lattice, which impacts diffusion.

A first-principles study of the diffusion of atomic oxygen in nickel

In this study, the coefficients of diffusion of oxygen in nickel-based alloys are determined by atomistically modeling the oxygen diffusion process using a vacancy-mediated diffusion model. Density functional theory is used to calculate the energy of the system. The activation barrier energy for the diffusion of atomic oxygen in nickel is quantified by determining the most favorable path, i.e., the minimum-energy path, for diffusion. Phonon analysis is performed using the direct force-constant method. The calculated pre-exponential factor for the lattice diffusion of oxygen in nickel is 5.45×10−7m2/s and the activation energy is 158.65kJ/mol.

Polypyrrole–NiO composite as high-performance lithium storage material

Organic electrode materials have long been proposed but their electrochemical performances are far from satisfactory in, for example, specific capacity and cycling stability, for secondary batteries. This article reports the electrochemical performance of a composite of polypyrrole (PPy) and nickel oxide (NiO), in which another lithium storage material, polypyrrole–nickel–oxygen (PPy–Ni–O) coordination complex, was fabricated during initial galvanostatically discharging. Extended X-ray absorption fine structure (EXAFS) spectroscopy and density functional theory (DFT) calculations indicate the process of the electrochemical formation of a PPy–Ni–O coordination and determine its multilayer structure. The strong and electrochemically stable coordination between the nickel and nitrogen atoms ensures the excellent electrochemical performances of the complex. These findings pave new ways to construct a new type of high-performance organic anode material for lithium ion batteries.

A simple expression for electronic stopping force of heavy ions in solids

A simple expression for the electronic stopping force of heavy ions in solids is proposed based on an adaption of the Bohr’s classical stopping theory. A three-parameter model is constructed by using experimental data for helium, oxygen, argon, krypton and xenon ions in carbon, aluminum, nickel and gold targets at energies from 600eV/u to 985MeV/u. Total average agreements between the model and used experimental data are (−4.5±47)% and (−1.6±7.4)% at energies below and above the Bragg peak, respectively. The good overall agreement makes this model a good candidate for future development in stopping force prediction tools.

Enhance of electrical properties of resistive switches based on Sr0.1Ba0.9TiO3 and TiO2 thin films by employing a Ni–Cr alloy as contact

We have investigated the electric-field-induced resistance-switching phenomena of ReRAM cells based on Sr 0.1 Ba 0.9 TiO 3 and TiO 2 thin films fabricated by rf-sputtering technique. Thin films were sandwiched between Pt, Ti and nichrome bottom electrode and Cu top electrode. The I – V measurements at room temperature are non-linear and hysteretic. Cells based on Sr 0.1 Ba 0.9 TiO 3 present a unipolar resistance-switching phenomenon and it is symmetric with respect to the voltage polarity, while cells based on TiO 2 have a bipolar resistance-switching with asymmetric behavior. From the I – V measurements we demonstrated that the nichrome enhance s the resistance-switching characteristics of the cells. A reduction of the voltage needed to achieve the HRS–LRS and LRS–HRS transitions are found and a very clear transition between these states is accomplished, in comparison with ReRAM cells fabricated with Pt and Ti electrodes, whose voltage values are large and no clear transitions are presented. This improvement in resistance-switching behavior can be explained due to O 2 vacancies formed in the interface because higher affinity for oxygen of nickel and chromium.

First-Principle Calculation of Monovacancy and Divacancy Interactions with Atomic Oxygen in Nickel: Thermal Expansion Effects

The insertion and diffusion energies of oxygen in presence of vacancies in nickel are studied by using the first-principle projector augmented waves (PAW). When the oxygen atom is located in a substitution site, the formation of a vacancy-oxygen pair is observed. Furthermore, we show that the formation of divacancies allows the oxygen atom to migrate more easily in the metal. A model for the migration process of the three-defect system is proposed. Finally, thermal expansion effects are included in our study; it is shown that temperature effects emphasize the diffusion.

Electrocatalytic action of nano-SiO2 with electrodeposited nickel matrix

The present work focuses on the electrocatalytic effect of nano-SiO2 on nickel electrodeposition and chemical interaction between nano-SiO2 and nickel in composite coating. The electrochemical behavior from n-SiO2/Ni composite brush plating system and quick nickel solution are investigated using cyclic voltammetry. The interaction between n-SiO2 particles and matrix metal nickel is researched by X-ray photoelectron spectrometry. The results show that the n-SiO2 take part in the electrode reaction during nickel electrocrystallization and can catalyze the nickel electrodeposition. The unsaturated bond of oxygen on n-SiO2 particles surface can capture some of the absorbed nickel atoms and form nickel–oxygen chemical bond. It is proved that the chemical binding interaction exists in the interface between nanoparticles surface and matrix metal nickel.

Investigations on the Diffusion of Oxygen in Nickel at 1000 ° C by SIMS Analysis

High-purity polycrystalline nickel foils have been oxidized at in laboratory air before being analyzed in secondary ion mass spectrometry to locally measure the oxygen content in solid solution. The values obtained in metallic grains are surprisingly the same before and after the oxidation treatments (between 5 and ) and they are much lower than the ones predicted from the literature solubility and diffusion coefficient data at . It is shown that this discrepancy could have its origins in the purity level of the samples but also in the exclusive oxygen diffusion in nickel grain boundaries. This last assumption is supported by the occurrence of nickel oxide particles on the walls of voids located in grain boundaries.

High-energy X-ray diffraction study of Ni-doped sodium metaphosphate glasses

The structures of four Ni-doped sodium metaphosphate glasses (NiO)x(NaPO3)1−x [x=0.009, 0.018, 0.033 and 0.074] were investigated by high-energy synchrotron X-ray diffraction (E=120.0keV). With increasing NiO content the development of the first nickel–oxygen correlation could clearly be observed in the corresponding pair correlation functions. The high-resolution X-ray diffraction data enabled the separation of the first Ni–O, Na–O and O–O correlations for a-(NiO)0.074(NaPO3)0.926. The first average Ni–O distance is 2.02(2)Å and the coordination of Ni with O, which was also determined by EXAFS at the Ni K-absorption edge, is 6. Interatomic distances between phosphorus and bridging (P–OB) or non-bridging oxygen (P–OT) could be discriminated in the structures of all investigated samples.

Synthesis and crystal structure of Cu 2NiO(B 2O 5) and Cu 2MgO(B 2O 5)

A transport reaction synthesis technique has been used to prepare single crystals of two pyroborate compounds having the formulas Cu 2NiO(B 2O 5) and Cu 2MgO(B 2O 5). The two compounds are isostructural and crystallize in the monoclinic space group P2 1/ c. Cu 2NiO(B 2O 5): a=3.2003(10), b=14.775(3), c=9.097(3), β=93.28(4), V=429.4(2) Å 3, Z=4; and Cu 2MgO(B 2O 5): a=3.2401(6), b=14.790(2), c=9.147(2), β=94.88(2), V=436.7(2) Å 3, Z=4. The structures of Cu 2NiO(B 2O 5) and Cu 2MgO(B 2O 5) were, respectively, refined from 804 and 1000 independent reflections to the final residuals R1=0.0366, wR2=0.0911 and R1=0.0231, wR2=0.0644. Both compounds exhibit a chevron-like structure built up of ribbons, made of edge-connected copper and nickel–oxygen polyhedra, running along the (1 0 0) direction. These ribbons are connected from one another via oxygen atoms and the cohesion of the three-dimensional network is ensured by [B 2O 5] entities. Cu in part occupies the position for Ni or Mg, so that the compounds actually are solid solution compounds. Ni or Mg atoms are octahedrally coordinated by oxygen, while the two pure Cu sites show [4] and [4+1] coordination, for Cu(1) and Cu(2), respectively. The ELNES B-K edge spectra for the two compounds support that the borate group present is [B 2O 5].

Transcriptional regulation of Nostoc hydrogenases: effects of oxygen, hydrogen, and nickel.

The transcription of structural genes encoding two hydrogenases in N(2)-fixing cultures of the cyanobacteria Nostoc muscorum and Nostoc sp. strain PCC 73102 were examined by reverse transcription-PCR. A low level of oxygen and addition of nickel induce higher transcript levels of both hydrogenases, whereas molecular hydrogen has a positive effect on the transcription of the genes encoding only the uptake hydrogenase.