Showing papers on "Nickel boride published in 2010"
TL;DR: The ternary boride was prepared by sintering a mechanically milled mixture of MgB_2 and Ni precursors at 975 °C under inert atmosphere as mentioned in this paper.
Abstract: We report that a ternary magnesium nickel boride (MgNi_(2.5)B_2) mixed with LiH and MgH_2 can be hydrogenated reversibly forming LiBH_4 and Mg_2NiH_4 at temperatures below 300 °C. The ternary boride was prepared by sintering a mechanically milled mixture of MgB_2 and Ni precursors at 975 °C under inert atmosphere. Hydrogenation of the ternary, milled with LiH and MgH_2, was performed under 100 to 160 bar H_2 at temperatures up to 350 °C. Analysis using X-ray diffraction, Fourier transform infrared, and ^(11)B magic angle spinning NMR confirmed that the ternary boride was hydrogenated forming borohydride anions. The reaction was reversible with hydrogenation kinetics that improved over three cycles. This work suggests that there may be other ternary or higher order boride phases useful for reversible hydrogen storage.
26 citations
TL;DR: In this paper, 1,3-Dithiolanes are rapidly cleaved by nickel boride, generating corresponding hydrocarbons in excellent yields, and the hydrogenolysis is rapid at room temperature and does not require protection from the atmosphere.
23 citations
TL;DR: In this article, a network-like carbon nanotube (CNT) films free of polymer binder were deposited directly onto a stainless steel substrate by electrophoresis.
22 citations
TL;DR: The enthalpies of formation of the nickel boride phases, as well as the lattice stability, were calculated using density functional theory and density functional perturbation theory methods.
Abstract: We report the formation of nickel borides, at room temperature and pressure, from the decomposition of NaBH4 promoted by the addition of nickel bromide at different concentrations in a dispersing organic medium, tetrahydrofuran and pentane. The nickel borides, formed as amorphous powders, were analyzed, and the structure information served as input for modeling a periodic lattice structure with the same composition. Experimentally, the nickel boride phases were predominantly composed of a boron-rich phase with composition NiB3. Combining FT-IR, X-ray diffraction analyses, and theoretical structure determination, we suggest for it a monoclinic structure, with symmetry group P21/c, lattice parameters a =3.038 A, b = 8.220 A, c = 5.212 A, α = β = 90.00° and γ = 87.57°. The enthalpies of formation of the nickel boride phases, as well as the lattice stability, were calculated using density functional theory and density functional perturbation theory methods.
19 citations
TL;DR: In this paper, a dendrimer-ligand-based method employing amine-terminated poly(propylene imine)-dendrimers, DAB-Amn, was used to derive low-size-dispersity (±8−21%) crystalline Ni(0) nanoparticles.
Abstract: Reported here is the highly controlled synthesis and subsequent characterization of low-size-dispersity (±8−21%) crystalline Ni(0) nanoparticles derived from a dendrimer-ligand-based method employing amine-terminated poly(propylene imine) dendrimers, DAB-Amn. Crystalline Ni(0) nanoparticles devoid of any nickel boride are obtained by anaerobic borohydride reduction in methanol of DAB-Amn−Ni(II)x, as determined by high-resolution X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), and selected-area electron diffraction (SAED) measurements. Nickel nanoparticles with highly tunable diameters ranging from l.9 to 2.7 nm are readily obtained by methanolic borohydride reduction of Ni(II) coordinated to the primary amines of five different generations of DAB-Amn (n = 4, 8, 16, 32, 64). Control over the diameter of the Ni nanoparticles is readily achievable and inversely related to dendrimer generation and the NH2:Ni(II) ratio, n/x. These outcomes bode well for future...
17 citations
TL;DR: In this article, a reaction couple of sintered boron suboxide, nickel and green compact B6O were assembled and heat-treated at 1850 8C for 20 min.
11 citations
TL;DR: Passivity degradation by lead and the inhibitive mechanism of nickel boride were explained by a defect chemistry in an oxide semiconductor and an adhesion preference as a function of the wetting angle, respectively.
Abstract: Even though nickel based Alloy 600 (Ni 75 wt%, Cr 15 wt% and Fe 10 wt%) shows superior corrosion and mechanical properties, numerous corrosion problems, caused by a long time exposure of more than 30 years under a high temperature and high pressure water chemical environment have occurred. Especially, a lead induced stress corrosion cracking (SCC) has been a very important issue. A SCC is deeply related to a nano-sized oxide properties, formed on an Alloy 600 surface, because a crack initiates and propagates through a breakdown and modification of a thin surface oxide formed naturally on Alloy 600 in an aqueous solution. Therefore an investigation of an oxide properties would provide key information to elucidate the mechanism of a SCC and to establish a countermeasure. In the present work, a surface oxide film formed on Alloy 600 in an aqueous solution at 315 degrees C without/with a lead oxide and nickel boride as a SCC accelerator and an inhibitor, respectively, was analyzed by using a transmission electron microscopy, equipped with an energy dispersive X-ray spectroscopy and an X-ray photoelectron spectroscopy, equipped with an ion sputter for a depth profiling. In both the ammonia solutions without/with NiB, a duplex oxide layer was formed, i.e., a porous outer oxide mainly composed of NiO and Ni(OH)2 and a relatively dense inner Cr2O3 layer. Lead was incorporated into the oxide layer leading to a Cr depletion in the oxide layer and a passivity degradation. The passivity of the surface oxide was increased when NiB was added into a solution with PbO, which was in accordance with the increase of the SCC resistance. Passivity degradation by lead and the inhibitive mechanism of nickel boride were explained by a defect chemistry in an oxide semiconductor and an adhesion preference as a function of the wetting angle, respectively.
5 citations
4 citations
TL;DR: In this article, chirallanthanide(III) salt complexes of 3,3′-bis[diethylamino]-methyl-]-1,1′-binaphthalene-2,2′-diol(Binolam) were examined as catalysts for the enantioselective addition of nitromethane to alkyl, aryl, or alkynyl trifluoromethyl ketones.
Abstract: Enantiomerically enriched trifluoromethyl-substituted alcoholshaving a quaternary center of chirality can be prepared by the catalyticenantioselective addition of carbon nucleophiles to trifluoromethylketones, trifluoropyruvates, or the like. In particular, chirallanthanide(III) salt complexes of 3,3′-bis[(diethylamino)--methyl-]-1,1′-binaphthalene-2,2′-diol(Binolam) were examined as catalysts for the enantioselective additionof nitromethane to alkyl, aryl, or alkynyl trifluoromethyl ketones.The corresponding nitro-aldols were obtained in moderatechemical yields and good enantio-selectivities. The absoluteconfiguration of the product was determined to be S whenthe lanthanum complex (Δ ,S,S,S)-[(Binolam-) 3 La(OTf) 3 ] wasused as a catalyst (25 mol%) in the presence of an equivalentamount of 1,8-bis(dimethylamino)naphthalene in anhydrous acetonitrile.The nitroaldol adducts were reduced to the corresponding amino alcoholsby nickel boride (nickel chlor-ide/sodium tetrahydroborate)in methanol.
2 citations
1 citations
TL;DR: In this paper, the effects of lead on the properties of the surface passive films were investigated and the effect of a nickel boride inhibitor was evaluated, which significantly reduced the susceptibility of the alloy to a lead-induced stress corrosion cracking (PbSCC).
Abstract: Corrosion-resistant nickel-based Alloy 600 is susceptible to a lead-induced stress corrosion cracking (PbSCC) in aqueous solutions. The lead species incorporated into the oxide at the alloy surface degrade the passivity and cause a PbSCC. Effects of lead on the properties of the surface passive films were investigated. The cross sections of the surface films were examined by a transmission electron microscopy and the species present in the films were analyzed with an energy dispersive x-ray spectroscopy and an x-ray photoelectron spectroscopy. In-depth concentration profiles of the species were analyzed by using an ion sputtering technique. The electrochemical impedance spectroscopy technique was used to characterize the electrochemical behaviors. Effectiveness of a nickel boride inhibitor was also evaluated. The boride inhibitor altered the properties of the resultant passive film, and significantly reduced the susceptibility of the alloy to a PbSCC.