Nickel amorphous

Yu. Koltypin, G. Katabi, X. Cao, R. Prozorov, and A. Gedanken, The sonochemical preparation of amorphous nickel, J. Non-Cryst. Solids, in press. ... 

The passive films formed by the addition of sufficient amounts of valve metals to amorphous nickel-valve-metal alloys are exclusively composed of valve-metal oxyhydroxides or oxides such as TaOjCOH) , Nb02(OH) or TajO,. Consequently, amorphous alloys containing strongly passivating elements, such as chromium, niobium and tantalum, have a very high ability... 

Ramesh S, Yuri K, Ruslan P, Aharon G (1997) Sonochemical deposition and characterisation of nanophasic amorphous nickel on silica microspheres. Chem Mater 9 546-551... 

In ethanol nickel(II) acetate treated with NaBFLt produces a nearly colloidal black suspension63. Variation of the solvent in the preparation of the nickel catalyst results in an amorphous nickel boride catalyst67,68. This P-2 nickel catalyst is much more sensitive to the double-bond structure69,70. In the hydrogenation of the strained double bonds of nor-bomadienes, P-2 nickel shows high selectivity (95%) and low isomerization characteristics (equations 20 and 21). 

The films are epitaxial in the sense that the lattice constant is intermediate between those of copper and nickel. As indicated above, that modulated strain is probably responsible for the increased hardness. Other authors (5) have tried to explain similar effects by stating that the layers were specifically oriented. Our example (6) demonstrates that these considerations must be reexamined since it was possible to achieve the effect in a crystalline multilayer deposited on an amorphous nickel-phosphorus underlayer. It appears that layer thickness is the important parameter here. 

Nickel oxide (black and green) amorphous nickel sulfide nickel subsulfide nickel chloride nickel sulfate nickel acetate... 

The deposit does not contain sulfur in a well-defined stoichiometry but is a mixture of different nickel sulfides, in particular Ni2S3, and amorphous nickel (72). It is not really clear whether the catalytic activity is due to amorphous nickel [compare Kreysa (55)] or to Ni2S3. A comparison of the... 

K. Tamura and H. Endo, Eerromagnetic Properties of Amorphous Nickel, Physics Letters, Vol.29A, 1969, pp.52-53. 

Metallic nanopartides were deposited on ceramic and polymeric partides using ultrasound radiation. A few papers report also on the deposition of nanomaterials produced sonochemically on flat surfaces. Our attention will be devoted to spheres. In a typical reaction, commerdally available spheres of ceramic materials or polymers were introduced into a sonication bath and sonicated with the precursor of the metallic nanopartides. In the first report Ramesh et al. [43] employed the Sto-ber method [44] for the preparation of 250 nm silica spheres. These spheres were introduced into a sonication bath containing a decalin solution of Ni(CO)4. The as-deposited amorphous clusters transform to polyciystalline, nanophasic, fee nickel on heating in an inert atmosphere of argon at a temperature of 400 °C. Nitrogen adsorption measurements showed that the amorphous nickel with a high surface area undergoes a loss in surface area on crystallization. 

Gedanken and his group were searching to replace the Ni(CO)4, which was the source for the preparation of nickel, and is known to be a hazardous material. They found [67] a new precursor for the sonochemical preparation of amorphous nickel, Ni(cyclooctadiene)2, which yielded relatively large (200 nm) amorphous nanoparticles composed of nickel and carbon atoms. Small nickel particles were dispersed all over the particle. When these particles were heated slightly above their crystallization temperature, much smaller particles (5 nm) of encapsulated crystalline nickel in amorphous carbon were obtained. The XPS spectrum reveals that the crystallization process is also accompanied by the reduction of the surface Ni+ ions by the amorphous carbon atoms. The DSC measurements substantiate this assumption. 

Weber, T. A., and Stillinger, F. H., Interactions, local order, and atomic rearrangement kinetics in amorphous nickel-phosphorus alloys. Phys. Rev. B 32,5402 (1985). 

J. C. Barbour The Diffusion of Nickel in Amorphous Nickel-Zirconium Alloys and the Composition Analysis of Nickel-Silicide Formation in Lateral Diffusion Couples. Ph.D. Thesis, Dept, of Mater. Sci. Cornell Univ., (1986)... 

It has been demonstrated that there are two types of sites on nickel surface [5]. (1) The site with affinity for TA where e.d. hydrogenation takes place (e.d. site). This site would locate on the surface of the crystallite nickel. (2) The site without affinity for TA where racemic products are produced (non-enantio-differentiating site (non-e.d. site)). This site would locate on the surface of aluminum derivatives or the amorphous nickel. The e.d. ability of the catalyst was represented by both the intrinsic e.d. ability of the modification reagent and the ratio of the optically active compounds produced on the e.d. site to the racemates produced on the non-e.d. site. Therefore, one of the effective strategies for raising the e.d. ability of the catalyst is to investigate the various catalyst preparation conditions in order to remove the non-e.d. site from the catalyst surface. 

Selective catalytic hydrogenation of bifiinctional compounds over amorphous nickel alloys... 

Kumagai K., Samata Y., Kawashima A., Asami K. and Hashimoto K. (1987) Anodic characteristics of amorphous nickel-valve metal alloys containing small amounts of platinum group elements in 0.5 M NaCl. J. appl. J. electrochem. 17, 347-356. 

Nanocrystalline and amorphous nickel-boron films with different boron content were prepared by electrodeposition. Ability of various boron-containing compounds to be a source of boron was studied. Effects of boron content on the crystallite size, surface morphology, microhardness and wear resistance of the films were investigated. It was shown that the Ni-B films containing less than 14 at. % of boron had the nanocrystalline structure. The films became amorphous at boron content more than 14 at. %. Boron incorporation into nickel film and increasing the content of boron resulted in a decrease of the crystallite size, extension of grain boundaries and considerable increase in microhardness and wear resistance. 

Test Compounds. Nickel subsulfide (crystalline oNi3S2, particle size < 5 ym) was provided by Dr. Edward Kostiner, University of Connecticut, and its purity and crystal structure were verified by emission spectroscopy and X-ray diffractometry as previously described (L5 - Amorphous nickel monosulfide (NiS) was precipitated by addition of aimnonium sulfide to a solution of NiCl2 that was prepared from carbonyl-derived Ni dust and ultrapure HCl. The amorphous NiS was devoid of crystal structure, based upon X-ray diffractometry. The aNi3 2 and NiS powders were sterilized by washing in acetone immediately prior to suspension in tissue culture medium. 

Studies in which nickel was administered via inhalation are limited. Studies on hamsters and rats with insoluble nickel oxide showed poor absorption, with retention of much of the material in the lungs after several weeks [25]. In contrast, absorption of soluble nickel chloride or amorphous nickel sulfide was rapid. 

Poly (maleic anhydride) is produced in approximately a 70% yield when a mixture of the monomer and a catalytic amount of amorphous nickel... 

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