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181.
Influence of boric acid on the electrochemical deposition of Ni 总被引:1,自引:0,他引:1
M. Šupicová R. Rozik L. Trnková R. Oriňáková M. Gálová 《Journal of Solid State Electrochemistry》2006,10(2):61-68
The electrolytic deposition of Ni onto a paraffin-impregnated graphite electrode from supporting chloride electrolyte (0.5 mol dm−3 NaCl) adjusted to the required pH using dilute HCl is investigated. The effect of electrolyte composition on the Ni electrodeposition
is studied using linear sweep voltammetry in the cathodic region. An elimination voltammetry procedure was applied to evaluate
the polarization curves. The aim of this work was to deduce the mechanism of Ni reduction in the chloride bath as well as
the influence of boric acid on this. Positively-charged NiCl+ ions were found to be the electroactive particles in the Ni reduction mechanism. The strong competition between the NiCl+, Cl− and H+ ions for active sites at the electrode is discussed. Kinetically-controlled adsorption/desorption processes of various species
were also confirmed using elimination voltammetry with a linear scan. The evolution of gaseous hydrogen, catalyzed by the
freshly-deposited Ni, accompanies the electrodeposition process. The presence of boric acid at a sufficiently high concentration
inhibits the deposition of Ni and, at the same time, improves the morphology and brightness, as well as the adhesion of the
deposited Ni.
Elimination voltammetry with a linear scan is an efficient way to evaluate current–potential curves that reflect the electrodeposition
of one-component Ni coatings. By eliminating selected currents, additional interesting and useful information can be obtained
from voltammetric data. 相似文献
182.
183.
184.
185.
L. N. Luk’yanova V. A. Kutasov V. V. Popov P. P. Konstantinov 《Physics of the Solid State》2006,48(4):647-653
The galvanomagnetic and thermoelectric properties of n-Bi2-x SbxTe3-y-z SeySz multicomponent solid solutions with atomic substitutions (Sb → Bi; Se, S → Te) are studied. The principal components of the effective mass tensor (m 1, m 2, m 3) for the isotropic mechanism of charge carrier scattering are determined within a many-valley model of the energy spectrum for compositions 0.08 ≤ x ≤ 0.4 and 0.06 ≤ y = z ≤ 0.15. The effect of a variation in the parameters of the constant-energy surface on the thermoelectric efficiency is analyzed for different compositions and carrier concentrations in solid solutions. 相似文献
186.
J. Balogh D. Kaptás L. F. Kiss T. Kemény L. Bujdosó I. Vincze 《Hyperfine Interactions》2006,169(1-3):1343-1347
Magnetic multilayers of 57Fe with nominal thickness, T
nom, between 0.4 and 1.0 nm separated by 3.0 nm Al spacer layers were prepared by alternate deposition of the constituents in
high vacuum. The samples were investigated at 4.2 K in external magnetic field. A fraction of Fe atoms corresponding to about
0.3 nm equivalent Fe-thickness was found to mix into the Al spacer. The extremely strong magnetic anisotropy observed for
T
nom < 0.8 nm is attributed to Fe layers of approximately two atomic planes thick. The anisotropy decreases considerably after
the building up of the third Fe atomic layer starts at T
nom = 0.8 nm, but full saturation was not achieved even for T
nom = 1 nm and 3 T magnetic field applied perpendicularly to the sample plane. 相似文献
187.
The stoichiometric reactions of trimethylaluminum with 2,6‐(MeOCH2)2C6H3OH (LH) revealed compounds L3Al ( 1 ) and L2AlMe ( 2 ). On the other hand reaction of 1 equiv. of LH with trimethylaluminum did not lead to the formation of complex LAlMe2 ( 3 ), rather 2 together with Me3Al were observed as a result of a disproportionation of 3 . Compounds 1 and 2 were characterized by elemental analysis, 1H and 13C NMR spectroscopy and in the case of 1 by X‐ray diffraction. Derivative 2 underwent transmetalation with Ph3SnOH, giving LSnPh3 ( 4 ) as the result of a migration of ligand L from the aluminum to the tin atom. The identity of 4 was established by elemental analysis, 1H, 13C and 119Sn NMR spectroscopy and 1H, 119Sn HMBC experiments. The system 2 and B(C6F5)3 in a 1:1 molar ratio was shown to be active in the polymerization of propylene oxide and ε‐caprolactone. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
188.
Abull is the (self-complementary) graph with verticesa, b, c, d, e and edgesab, ac, bc, bd, ce; a graphG is calledBerge if neitherG not its complement contains a chordless cycle whose length is odd and at least five. We prove that bull-free Berge graphs are perfect; a part of our argument relies on a new property of minimal imperfect graphs.This work was done while both authors were at the School of Computer Science, McGill University; support by NSERC is gratefully acknowledged. 相似文献
189.
Suppose that K
d is compact and that we are given a function fC(K) together with distinct points xiK, 1in. Radial basis interpolation consists of choosing a fixed (basis) function g :
+→
and looking for a linear combination of the translates g(|x−xj|) which interpolates f at the given points. Specifically, we look for coefficients cj
such that
has the property that F(xi)=f(xi), 1in. The Fekete-type points of this process are those for which the associated interpolation matrix [g(|xi−xj|)]1i,jn has determinant as large as possible (in absolute value). In this work, we show that, in the univariate case, for a broad class of functions g, among all point sequences which are (strongly) asymptotically distributed according to a weight function, the equally spaced points give the asymptotically largest determinant. This gives strong evidence that the Fekete points themselves are indeed asymptotically equally spaced. 相似文献
190.
Singularity patterns in a chemotaxis model 总被引:3,自引:0,他引:3