Showing papers on "Nickel published in 1992"
TL;DR: The synthesis of molecular-based ferromagnetic materials was investigated in this article, where special attention was given to the T{sub c} value and its relation to the stoichiometry and water content.
Abstract: The synthesis of molecular-based ferromagnetic materials was investigated. Special attention was given to the T{sub c} value and its relation to the stoichiometry and water content. 12 refs., 2 figs.
376 citations
TL;DR: In this paper, a review describes Schiff bases of potential biological interest; for example, nickel compounds have been used in jack beam urease and in some hydrogenases, and the use of these compounds in catalytic reactions has also been considered.
341 citations
TL;DR: In this article, the authors used the complete active space SCF method and second-order perturbation theory to study the nickel atom's energy in the presence of a single atom.
188 citations
TL;DR: The bulk H atom is shown to be the reactive species in the hydrogenation of CH3 adsorbed on Ni(111) to form CH4, while the H atoms bound to the surface were unreactive.
Abstract: Studies in heterogeneous catalysis have long speculated on or have provided indirect evidence for the role of hydrogen embedded in the catalyst bulk as a primary reactant. This report describes experiments carried out under single-collision conditions that document the distinctive reactivity of hydrogen embedded in the bulk of the metal catalyst. Specifically, the bulk H atom is shown to be the reactive species in the hydrogenation of CH 3 adsorbed on Ni(111) to form CH 4 , while the H atoms bound to the surface were unreactive. These results unambiguously demonstrate the importance of bulk species to heterogeneous catalytic chemistry.
182 citations
TL;DR: Optically active pyridine derivatives 2, 15, 18, 19, 21, 26, and 27 were obtained by enantioselective reduction of the corresponding ketones 5, 7, 11-13, 24, and 25 using the chiral borane reagent chlorodiisopinocampheylborane [(Ipc)2BCl] as mentioned in this paper.
Abstract: Optically active pyridine derivatives 2, 15, 18, 19, 21, 26, and 27 are obtained by enantioselective reduction of the corresponding ketones 5, 7, 11–13, 24, and 25 using the chiral borane reagent chlorodiisopinocampheylborane [(Ipc)2BCl]. Nickel(0)-mediated coupling of bromopyridines 2, 15, and 31 gives C2-symmetric 2,2′-bipyridines (R,R)-32, (R,R′)-33, and (S,S)-38, respectively, which form metal complexes with CoII, PdII, CuI, and AgI. Aryl-substituted pyridines 26, and 39–41 are synthesized by palladium(0)-catalyzed cross couplings of 2 and 15 with boronic acids 42–44.
181 citations
TL;DR: A series of nickel-aluminum mixed hydroxides was prepared by coprecipitation and their structure and composition was examined by X-ray diffraction and thermal analysis as mentioned in this paper.
178 citations
TL;DR: Analysis of different types of alloys used in orthodontics found the largest amount of nickel and chromium were leached out from the face-bows and the least amount from the arch wires, and Soldered stainless steel face- Bows seemed to be very susceptible to corrosion.
158 citations
TL;DR: In this article, the adsorption on silica of various amminenickel(II) complexes has been investigated as a function of the preparation procedure, i.e., the composition of the impregnating solution and the washing and drying steps.
Abstract: The adsorption on silica of various amminenickel(II) complexes has been investigated as a function of the preparation procedure, i.e., the composition of the impregnating solution and the washing and drying steps. Quite different adsorption modes can he distinguished by EXAFS, XANES, and infrared spectroscopies depending on the pH of the impregnating solution
149 citations
142 citations
TL;DR: The X-ray structures of β-substituted pyrrole, its nickel(II) complex (NiTMOBP), and the nickel-II derivative are reported in this paper.
Abstract: The X-ray structures of the β-substituted-pyrrole, its nickel(II) complex (NiTMOBP), and the nickel(II) derivative are reported. The synthesis of the free base H 2 TPFPOBP is also described. All these molecules are nonplanar, displaying saddle-shaped conformations
142 citations
Patent•
30 Apr 1992
TL;DR: A high performance, durable, low-E glass exhibiting about 80% or more visible transmittance, a hemispherical emissivity (E h ) of about 0.13 or less, and a normal emissivities (E n ) of approximately 0.10 or less is formed by sputter-coating a layer system on the glass substrate which comprises an undercoat and overcoat of Si 3 N 4, at least one silver layer, and at least two sandwiching layers of a nickel or nickel alloy, preferably with the nickel alloy being nichrome,
Abstract: A high performance, durable, low-E glass exhibiting about 80% or more visible transmittance, a hemispherical emissivity (E h ) of about 0.13 or less, and a normal emissivity (E n ) of about 0.10 or less is formed by sputter-coating a layer system on the glass substrate which comprises an undercoat and overcoat of Si 3 N 4 , at least one silver layer, and at least two sandwiching layers of a nickel or nickel alloy, preferably with the nickel alloy being nichrome, and the chromium being in the form of a nitride thereof.
TL;DR: In this article, a spin-polarised Green's-function technique based on the linear muffin-tin orbitals method within the tight-binding and atomic sphere approximations was used to calculate magnetic moments, work functions, and surface energies for several of the most closely packed surfaces of iron, cobalt, and nickel.
Abstract: We have calculated magnetic moments, work functions, and surface energies for several of the most closely packed surfaces of iron, cobalt, and nickel by means of a spin-polarised Green's-function technique based on the linear muffin-tin orbitals method within the tight-binding and atomic sphere approximations. We find enhanced spin moments at all the surfaces considered except for Ni fcc(111), where the moment at the surface reverts to its bulk value. This is in close agreement with earlier slab calculations
Journal Article•
TL;DR: In this article, large-scale molecular dynamics simulations of atomistic mechanisms of adhesive contact formation, friction, and wear processes were performed using several tip and substrate materials, including intermetallic (nickel and gold), interionic (CaF2), and thin alkane (n-hexadecane) films adsorbed on a metal (gold) surface and interacting with a metal tip.
TL;DR: In this article, the electrochemical impregnation of porous nickel sintered plates has been investigated to gain a better understanding of the structure, tenure, and composition of the deposited active material.
Abstract: The electrochemical impregnation of porous nickel sintered plates has been investigated to gain a better understanding of the structure, tenure, and composition of the deposited active material. It was found that the nature of this material depends on the temperature of the impregnation bath. Below 60 o C, an α-type nickel hydroxide forms, while above 60 o C this same α phase appears simultaneously with βNi(OH) 2 and a crystallized phase in major proportion exhibiting structural features similar to those of nickel hydroxy-nitrate
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TL;DR: In this paper, the status of nickel in hardmetals and cermets was reviewed and it was shown that attractive alternatives to WCCo are possible, both by replacement or partial replacement of the cobalt with nickel and by changing the approach completely by using the alternative hard phase of TiCN bonded with nickel to form cermet, together with altering the machining philosophy.
Abstract: The literature has been reviewed to determine the status of nickel in hardmetals and cermets. It has shown that attractive alternatives to WCCo are possible, both by replacement or partial replacement of the cobalt with nickel and by changing the approach completely by using the alternative hard phase of TiCN bonded with nickel to form cermets, together with altering the machining philosophy.
Patent•
09 Dec 1992
TL;DR: In this paper, a heat treatable sputter-coated layer system for glass substrates was proposed, where the layer system includes a metallic layer of nickel or a high nickel content alloy covered by a separate layer of metallic silicon or an oxide of nickel.
Abstract: A heat treatable sputter-coated layer system for glass substrates may be applied before heat treatment if the layer system includes a metallic layer of nickel or a high nickel content alloy covered by a separate layer of metallic silicon or an oxide of nickel or the high nickel content alloy, which in turn is covered by a protective metal oxide such as stoichiometric Sn 02.
TL;DR: In this article, isothermal stress relaxation and differential temperature measurements were used to determine the activation enthalpy and activation area for dislocation motion in nickel and the effects of hydrogen and carbon on these parameters.
Abstract: Deformation experiments were performed to determine the effects of hydrogen and carbon on the activation parameters for dislocation slip in nickel. The techniques used were isothermal stress relaxation and differential temperature measurements. These methods allowed determination of the activation enthalpy and activation area for dislocation motion in nickel and the effects of hydrogen and carbon on these parameters. The results show that hydrogen increases the dislocation mobility in Ni and in NiC alloys by reducing the activation enthalpy for dislocation motion, while carbon reduces the dislocation mobility by increasing the activation enthalpy. Hydrogen solutes decrease the activation area for dislocation motion in both pure Ni and in NiC alloys.
TL;DR: Magnetic and transport properties of the layered (R 3¯ m ) metastable system Li 1−δ− x Ni 1+δ O 2 and the cubic spinel Li[Ni 2 ]O 4 are reported for samples prepared from (Li 1− δ Ni δ )NiO 2, δ=0.04 and 0.08, by chemical extraction of lithium with NO 2 PF 6 at room temperature as discussed by the authors.
TL;DR: In this article, the influence of various variables on the performance of the ruthenium catalysts is continued, such as the type of reaction modifying salt, its concentration, the method of pretreatment of the catalyst, the pH of the aqueous phase and the impact of iron deposition from the inner wall of the reactor on the surface of the catalysts.
Abstract: The research described in this article forms a continuation of the investigations reported in partI [J. Struijk, M. d'Angremond, W.J.M. Lucas-de Regt and J.J.F. Scholten, Appl. Catal. A, 83 (1992) 263], concerning the batch-wise partial hydrogenation of benzene to cyclohexene in a stirred autoclave at 423 K and a pressure of 5.0 MPa, over ruthenium catalysts and in the presence of an aqueous salt solution. In the present part, the study of the influence of various variables on the performance of the catalyst is continued. Attention is paid to the influence of the type of reaction-modifying salt, its concentration, the method of pretreatment of the catalyst, the pH of the aqueous phase and the influence of iron deposition from the inner wall of the reactor on the surface of the catalyst. Fresh and used catalysts were characterized by BET surface area measurements, X-ray photoelectron spectroscopy/Auger electron spectroscopy analysis, atomic absorption spectroscopy and temperature-programmed reduction. From these characterizations the coverage of the ruthenium catalysts with the reaction-modifying salts could be determined. As stated before, the primary function of the adsorbed salts appears to be the transformation of the hydrophobicity of the ruthenium catalyst particles into hydrophilicity. Several salts can be used as a reaction-modifier, provided their adsorbability on ruthenium is high enough and reduction of the chemisorbed cations under the experimental conditions does not occur. Effective modifying salts are, for instance, chromium(II) sulphate, manganese(II) sulphate, iron(II) sulphate, cobalt(II) sulphate, nickel(II) sulphate, zinc(II) sulphate, zinc(II) chloride and gallium(III), cadmium(II) and indium (III) salts.
TL;DR: In this paper, discrete compounds resulting from the oxidation and oxygenation of nickel thiolate complexes have been isolated, separated, and characterized, and their properties have been described and compared.
Abstract: Discrete compounds resulting from the oxidation and oxygenation of nickel thiolate complexes have been isolated, separated, and characterized. Molecular oxygen or hydrogen peroxide reacted with [N,N'-bis(mercaptoethyl)-1,5-diazacyclooctane]nickel(II).
TL;DR: The time-dependent hydrogen evolution reaction (HER) on Ni electrodes shows a large increase in electrode over-potential with time, ascribed to hydride formation at active Ni cathode surfaces.
Abstract: The time-dependent hydrogen evolution reaction (HER) on Ni electrodes shows a large increase in electrode over-potential with time. This is ascribed to hydride formation at active Ni cathode surfaces. Hydride formation was detected by x-ray diffraction, morphological changes at the electrode surfaces, and resulting changes in secondary electron emissivities. Nickel electrodes annealed for 2 h in an argon atmosphere at 1000 o C after HER did not show x-ray lines assigned to hydride
TL;DR: In this article, the electrochemical properties of platinum, nickel and palladium derivatives of buckministerfullerene are described, and the properties of the palladium complex derivatives are analyzed.
Abstract: The electrochemical properties of platinum, nickel, and palladium complex derivatives of buckministerfullerene are described.
TL;DR: In this article, a variety of experimental techniques, including controlled atmosphere electron microscopy, thermogravimetry, and electrical conductivity measurements, were used to examine the structures of carbon filaments produced from the decomposition of hydrocarbons over copper-nickel and nickel catalysts.
TL;DR: In this paper, a compost-based sulfate-reduction system was used to treat nickel-contaminated mine waters, where simulated mine waters were adjusted to pH 4.5 and pumped through the columns at flow rates between 15 and 25 ml h−1.
Abstract: Experiments were done to determine if a compost-based sulfate-reduction system could be used to treat nickel-contaminated mine waters. Sulfate-reduction systems were established in columns containing acid-washed mushroom compost. Simulated mine waters containing 2000 mg sulfate 1−1 and 50–1000 mg nickel 1−1 were adjusted to pH 4.5 and pumped through the columns at flow rates between 15 and 25 ml h−1. Initially, almost all of the influent nickel was removed in the columns by sorptive and ion exchange mechanisms. The nickel removal rate then dropped to 18–30 mg nickel day (7.8 to 12.8 nmol g −1 compost day), where it remained relatively constant. The mechanisms responsible for the low and sustained rates of nickel removal on unamended compost are unclear. When sodium lactate was added to the inflow, sulfate reduction rates between 250 and 650 nmol day cm−3 compost were obtained and a sevenfold increase in the nickel removal rate was observed. The maximum nickel removal rate observed was 540 mg Ni kg−1 compost day (92 nmol Ni g−1 compost day) for columns receiving 1000 mg Ni 1−1.
Journal Article•
TL;DR: The time-dependent hydrogen evolution reaction (HER) on Ni electrodes shows a large increase in electrode over-potential with time as mentioned in this paper, which is ascribed to hydride formation at active Ni cathode surfaces.
Abstract: The time-dependent hydrogen evolution reaction (HER) on Ni electrodes shows a large increase in electrode over-potential with time. This is ascribed to hydride formation at active Ni cathode surfaces. Hydride formation was detected by x-ray diffraction, morphological changes at the electrode surfaces, and resulting changes in secondary electron emissivities. Nickel electrodes annealed for 2 h in an argon atmosphere at 1000 o C after HER did not show x-ray lines assigned to hydride
TL;DR: The properties of glassy carbon (GC) electrodes modified with tetraazamacrocyclic complexes of Ni(II) containing a pendant amino group have been studie the properties of a Ni-cyclam modified electrode.
TL;DR: In this article, a spinel-structured cobalt oxide with the spinel structure was used as an anode material for alkaline water electrolysis, which was prepared by thermal decomposition of nitrate precursors on titanium and nickel supports.
Abstract: Copper cobalt oxide with the spinel structure was investigated as an anode material for alkaline water electrolysis. This catalyst was prepared by thermal decomposition of nitrate precursors on titanium and nickel supports. Scanning electron microscopy analysis and electrochemical surface area measurements indicate that the electrodes are highly porous. Such preparation variables as the concentration of the mixed nitrates in isopropanol, the temperature of nitrate decomposition, the time of annealing, the catalyst loading, the nature of the substrate, the air flow during the thermal decomposition, and the cooling rate of the electrode have been investigated in detail to determine their influence on the morphology, the composition, the mechanical stability, and the electrocatalytic activity for oxygen evolution of the oxide films. It is shown that the performances can be ascribed to the variation in the roughness factor of the oxide layers. At 400°C, a resistive phase, presumably , is formed and dispersed on the surface of . This has a deleterious effect on the electrocatalytic activity. Copper cobalt oxide is oxidized and reduced prior to the oxygen evolution through a reaction which can involve the formation of the CoIV/CoIII redox couple on the surface of cobaltite. The material prepared on nickel at 275°C for 1 h at a catalyst loading of 3.3 mg cm−2 shows fairly low overvoltages for oxygen evolution.