Search results for "NICKEL"
showing 10 items of 1087 documents
Growth of passive layers on nickel during their voltammetric anodic dissolution in a weakly acid medium
2006
Abstract Quartz crystal microbalance in combination with voltammetry has been used for studying the electrochemical oxidation behaviour of a nickel deposit in a weakly acid medium. The instantaneous mass/charge ratio (Fdm/dQ) analysis allows to obtain the fraction of charge consumed in the passivation process, and, that way, the experimental kinetic equation of the passive layer growth. This experimental law has been fitted to the theoretical equation derived from the point defect model theory under voltammetric conditions.
Chloride role in the surface of nickel electrode
1998
The chloride ion participation in the dissolution process on nickel electrodes in acid media as well as in the formation of the passive layer and in the pitting corrosion induction were studied. Composite electrodes containing nickel powder dispersed in a polymeric matrix show similar processes to those observed in polycrystalline nickel. Furthermore, phenformine hydrochloride inhibits the dissolution process due to the adsorption of the organic cation on the metal surface, although it does not protect the metal from pitting corrosion. Electrochemical impedance spectroscopy data allowed us to propose a physical model for the role of chloride ion in the dissolution and passivation processes …
Determination of time dependence of passive layer on nickel from instantaneous mass/charge function F(dm/dQ) in competitive passivation/dissolution c…
2006
Nickel metal deposited on gold electrodes was studied in the passivity range of potentials under potentiostatic conditions and in a weakly acid sulphate medium. Mass and current variations during electrochemical experiments were analysed with the help of the instantaneous mass/charge ratio (Fdm/dQ). This analysis allows to obtain the intensity current component associated to the formation of a passive layer of Ni(OH)2, and, in this way, the experimental thickness growth. These experimental findings have been fitted to a theoretical model based on the point defect model theory for obtaining the time dependence of the thickness of the passive layer during the first stages of growth of the pas…
Effects of nano-scaled particles on endothelial cell function in vitro: studies on viability, proliferation and inflammation.
2004
Recent studies give support for a connection between the presence of inorganic particles (of microm and nm size) in different organs and tissues and the development of inflammatory foci, called granulomas. As the potential source of particles (e.g. porcelain dental bridges) and the location of particle detection were topographically far apart, a distribution via the blood stream appears highly probable. Thus, endothelial cells, which line the inner surface of blood vessels, would come into direct contact with these particles, making particle-endothelial interactions potentially pathogenically relevant. The objective of this study was to evaluate the effects that five different nano-scaled p…
Bioactive Co(II), Ni(II), and Cu(II) Complexes Containing a Tridentate Sulfathiazole-Based (ONN) Schiff Base
2021
New Co(II), Ni(II), and Cu(II) complexes were synthesized with the Schiff base ligand obtained by the condensation of sulfathiazole with salicylaldehyde. Their characterization was performed by elemental analysis, molar conductance, spectroscopic techniques (IR, diffuse reflectance and UV–Vis–NIR), magnetic moments, thermal analysis, and calorimetry (thermogravimetry/derivative thermogravimetry/differential scanning calorimetry), while their morphological and crystal systems were explained on the basis of powder X-ray diffraction results. The IR data indicated that the Schiff base ligand is tridentate coordinated to the metallic ion with two N atoms from azomethine group and thiazole ring a…
Study of passive films on stainless steels by photocurrent measurements
1990
Abstract Passive films formed on three different stainless steels have been studied by means of photocurrent spectroscopy. Differences in the photoelectrochemical behaviour have been attributed to the influence of the nickel content of the alloys and to the formation of different oxide phases.
Growth and optical properties of transition metal oxides single crystal solid solutions
2007
Abstract NiO, CoO, MnO single crystals and single crystal solid solutions of Ni c Mg 1− c O, Co c Mg 1− c O and Mn c Mg 1− c O were grown by the method of chemical transport reaction (the “sandwich” technique). The nature of the observed absorption and luminescence bands is explained in terms of the electronic transition of bivalent nickel, cobalt and manganese. The fine structure of the observed bands in NiO and MnO are connected to the pure exciton transition and to the exciton-magnon excitation.
Losses and depolarization of ultracold neutrons on neutron guide and storage materials
2017
At Institut Laue-Langevin (ILL) and Paul Scherrer Institute (PSI), we have measured the losses and depolarization probabilities of ultracold neutrons on various materials: (i) nickel-molybdenum alloys with weight percentages of 82/18, 85/15, 88/12, 91/9, and 94/6 and natural nickel Ni100, (ii) nickel-vanadium NiV93/7, (iii) copper, and (iv) deuterated polystyrene (dPS). For the different samples, storage-time constants up to $\ensuremath{\sim}460\phantom{\rule{0.16em}{0ex}}\mathrm{s}$ were obtained at room temperature. The corresponding loss parameters for ultracold neutrons, $\ensuremath{\eta}$, varied between $1.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and $2.2\ifmmode\t…
Behavior of one-magnon frequency in antiferromagneticNicMg1−cOsolid solutions
2005
The one-magnon scattering was studied in antiferromagnetic ${\mathrm{Ni}}_{c}{\mathrm{Mg}}_{1\ensuremath{-}c}\mathrm{O}$ solid solutions. We observed unpredicted behavior of both temperature and composition dependences of one-magnon excitation energies. First, the abrupt change of the one-magnon frequency by $7--8\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ occurs between $c=0.98$ and $c=0.9$ in the limit of $T\ensuremath{\rightarrow}0\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Second, upon increasing temperature, the one-magnon energy for highly diluted nickel oxide vanishes significantly below the N\'eel temperature.
Accessing the fundamentals of magnetotransport in metals with terahertz probes
2015
Spin-dependent conduction in metals underlies all modern magnetic memory technologies, such as giant magnetoresistance (GMR). The charge current in ferromagnetic transition metals is carried by two non-mixing populations of sp-band Fermi-level electrons: one of majority-spin and one of minority-spin. These electrons experience spin-dependent momentum scattering with localized electrons, which originate from the spin-split d-band. The direct observation of magnetotransport under such fundamental conditions, however, requires magnetotransport measurements on the same timescale as the electron momentum scattering, which takes place in the sub-100 fs regime. Using terahertz electromagnetic prob…