Showing papers on "Nickel published in 1977"

Resonant Photoemission in Nickel Metal

Abstract: A strong resonance effect has been observed for the first time in photoemission: This happens on a metallic nickel (100) surface when the photon energy is close to that of the $3p$ energy level. The effect is interpreted as the autionization of an excited quasidiscrete atomic configuration into a continuum of excitations with two holes in the $3d$ shell.

Measurement of the thermal-expansion coefficient of nickel from 300 to 1000 K and determination of the power-law constants near the Curie temperature

Abstract: A fused-quartz dilatometer was used to measure the thermal-expansion coefficient $\ensuremath{\alpha}$ of nickel between 300 and 1000 K. Measurements on National Bureau of Standards certified copper and tungsten standards with the dilatometer established the uncertainty in the $\ensuremath{\alpha}$ measurements on nickel as \ifmmode\pm\else\textpm\fi{} 0.8% (\ifmmode\pm\else\textpm\fi{}0.10 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}6}$ ${\mathrm{K}}^{\ensuremath{-}1}$), except within \ifmmode\pm\else\textpm\fi{} 2 K of the Curie temperature ${T}_{C}$ where the uncertainty was about \ifmmode\pm\else\textpm\fi{} 1.6%. Results of 38 investigations of the expansion of nickel reported in the literature were analyzed critically, resulting in a compilation of $\ensuremath{\alpha}$ of nickel from 0 to 1500 K. Theories of thermal expansion were employed to separate $\ensuremath{\alpha}$ into its paramagnetic ${\ensuremath{\alpha}}_{p}$ and magnetic ${\ensuremath{\alpha}}_{m}$ components. The calculated values of ${\ensuremath{\alpha}}_{m}$ near ${T}_{C}$ were fitted to the power-law equation, ${\ensuremath{\alpha}}_{m}=A({t}^{\ensuremath{-}a}\ensuremath{-}1){a}^{\ensuremath{-}1}+B$, that describes critical phenomena near the critical temperature [$t=(T\ensuremath{-}{T}_{C}){T}_{C}^{\ensuremath{-}1}$]. It was demonstrated that the critical exponents above and below ${T}_{C}$, $a$ and ${a}^{\ensuremath{'}}$, respectively, are the same as those derived from specific-heat measurements and that $a={a}^{\ensuremath{'}}=\ensuremath{-}0.093(\ifmmode\pm\else\textpm\fi{}0.010)$ in agreement with scaling laws of critical phenomena.

Carbene complexes. Part 12. Electron-rich olefin-derived neutral mono- and bis-(carbene) complexes of low-oxidation-state manganese, iron, cobalt, nickel, and ruthenium

Abstract: The electron-rich olefin [:[graphic omitted]R]2(LR2; R = Me or Et) provrdes a ready source of various thermally stable neutral mono- and bis-(carbene) complexes of Fe, Ru, Co, and Ni and, with greater difficulty, of MnI. Noteworthy is the range of co-ordination numbers, formal metal oxidation states, and geometries (tetrahedral, square planar, trigonal bipyramidal, or octahedral) of the complexes. Amongst the 29 new complexes are the novel neutral bis(carbene) specres [Fe(LMe)2(NO)2], [Co(CO)(LEt)2(NO)], trans-[Fe(CO)3(LMe)2], [Ni(CO)2(LEt)2], [Fe(CO)2l2(LMe)2], and [Ni(LMe)2(NO3)2]; the last is the only diamagnetic nickel(II) dinitrate. Infrared spectra show that ν(CO) is low compared with analogous (e.g. phosphine) complexes: ν(CN2) is in the range 1 480–1 540 cm–1, the upper end being characteristic of the higher-oxidation state metal complexes. This trend is also observed in 13C n.m.r. chemical shifts when Ccarb. moves to higher field (Ccarb. is generally 200–230 p.p.m. downfield from SiMe4); [Ru3(CO)11 LEt] shows only one CO resonance, an indication of fluxionality, whereas [Fe2(CO)(µ-CO)2(η-C5H5)LEt] exists at 25 °C in solution as a mixture of cis and trans isomers.

A review of the metabolism and toxicology of nickel.

Abstract: Although nickel is an essential element for animal nutrition, the physiological role of nickel is not yet established. Pathological alterations of nickel metabolism are recognized in several human diseases. The diverse clinical manifestations of nickel toxicology include: (1) acute pneumonitis from inhalation of nickel carbonyl, (2) chronic rhinitis and sinusitis from inhalation of nickel aerosols, (3) cancers of nasal cavities and lungs in nickel workers, and (4) dermatitis and other hypersensitive reactions from cutaneous and parenteral exposures to nickel alloys. The toxicity, carcinogenicity and embryotoxicity of nickel compounds in experimental animals are reviewed in this article, and consideration is given to the therapeutic use of chelating drugs in nickel poisoning.

A novel type of polycondensation of polyhalogenated organic aromatic compounds producing thermostable polyphenylene type polymers promoted by nickel complexes.

Abstract: Nickel complexes (NiCl2 (2,2′-bipyridine) and NiBr2(triphenylphosphine)2) catalyze polycondensation of di- and polyhalogenated aromatic compounds including p-dibromobenzene, p-dichlorobenzene, m-dichlorobenzene, bis (4-bromophenyl)ether, p-chlorobenzyl chloride and 1,3,5-trichlorobenzene by dehalogenation with magnesium to give polyphenylene type polymers in high yields.

A reinvestigation of takovite, a nickel aluminum hydroxy-carbonate of the pyroaurite group

Abstract: Samples from Takovo, Serbia (the type locality); Perseverance Mine, Agnew, Australia; and Var, France, were examined by X-ray powder diffraction, infrared and optical absorption spectroscopy, and thermogravimetric and chemical analysis. X-ray powder data are indexed with a hexagonal unit cell, and for the Takovo sample, a : 3.0250, c : 22.595 A; the o6served spacings conform with rhombohedral symmetry. The observed cell parameters are closely similar to those of pyroaurite and hydrotalcite. Spectroscopic and chemical data confirm the presence ol both molecular water and carbonate ions. The compositions of the Australian and Var samples approximate to NiuAlr(OH)r6(COs,OH) . 4HrO. Similar synthetic materials have been prepared by adding nickel and aluminum chlorides to a COr-saturated solution of NaOH and heating the product for 10 days or one month at 200-250"C and 1500 barswatervapor pressure.

Dissolution and passivation of nickel. An X-ray photoelectron spectroscopic study

Abstract: The presence and nature of surface species formed on a nickel electrode after polarisation in 0.5 mol dm–3 sulphuric acid and 0.5 mol dm–3 sulphuric acid + 0.005 mol dm–3 nickel sulphate has been investigated by X-ray photoelectron spectroscopy. The film produced in the active, prepassive, passive and transpassive regions was studied. Nine different species were detected including two sulphur species. In all cases the electrode was transferred to the spectrometer under nitrogen to minimise air oxidation of the metal or film.The binding energies and intensities of the photoelectron peaks were analysed and showed the presence of NiO and Ni(OH)2. The thickness of the film in the passive and transpassive regions was calculated, assuming a continuous layer, as 10–20 A.

Carbon dioxide)bis(trialkylphosphine)nickel complexes

Abstract: The reaction of [NiL4](L = PEt3 or PBun3) with CO2 in toluene affords complexes of formula [Ni(CO2)L2], via the [Ni(CO2)L3] species. The reaction of [Ni(CO2){P(C6H11)3}2]·0.75C6H5Me with O2 to give (peroxocarbonato)-bis( tricyclohexylphosphine)nickel(II) is also reported.

A Study of the Adsorption of Ni(II) and Cu(II) by Clay Minerals

Abstract: The adsorption of Ni(II) and Cu(II) on to the clay minerMs kaolinite, chlorite, and illite has been investigated. The quantity of Ni(II) at pH 6 and Cu(II) at pH 5 adsorbed has been found to vary in the manner chlorite > illite > kaolinite. Examination of the mode of bonding of the metal ions to the clay minerals using X-ray photoelectron spectroscopy (XPS) has been carried out. Compari- son of the binding energies for metal ions in octahedral sites in selected minerals (reference minerals) and in simple nickel and copper containing compounds with values for Ni(II) and Cu(II) adsorbed on chlorite indicate that nickel(II) is probably bound as the aquo ion while copper(II) may be adsorbed as Cu(OH) §

Carbonate precipitation for heavy metals pollutants

Abstract: A study was conducted to determine the hydroxide solubility for zinc, nickel, cadmium, and lead over a range of approximately pH 6 to 13; the determination of carbonate solubility for the same heavy metals over the same pH range, at selected carbonate concentrations; and a comparison of the residual soluble metal in the hydroxide system with that in the carbonate system. Based on the results of the study, hydroxide solubility can be predicted for cadmium and lead from published solubility constant values, and for zinc and nickel based upon experimental determined values presented. Also, solubility cannot be predicted based on equilibrium conditions for the carbonate system and that the kinetics of precipitation appear such for zinc and nickel that the carbonate form of these metals will not form within typical treatment plant detention times.

Critical‐point universality and fluids

Abstract: The similarity of critical behavior in dissimilar systems has long fascinated scientists. When Pierre Curie, in 1895, measured the magnetic equation of state of nickel, he was struck by how much the curves he obtained by plotting magnetization against temperature looked like the density–temperature isobars of carbon dioxide near the critical point. In 1907 Pierre Weiss fashioned his mean‐field theory describing the equation of state of nickel after Van der Waals's equation for fluids.