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Фокин, В. Н.; Фокина, Э. Э.; Тарасов, Б. П.; Коробов, И. И.; Shilkin, S. P.

doi:10.1023/a:1012318531279

Cited by 4 publications

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“…The specific surface area of La 5 Ni 5 H 0.5 (1.3 m 2 g 31 ) is substantially larger than that of hydrogen-treated LaNi 5 (0.23 0.3 m 2 g 31 ). The specific surface area of SmCo 5 H 0.3 (0.3 m 2 g 31 ) is similar to that of the sample prepared by the hydride dispersion procedure (0.27 m 2 g 31 ) [4].…”

supporting

confidence: 62%

“…Intermetallic compounds LaNi 5 and SmCo 5 (structural type CaCu 5 ) have a hexagonal lattice with the parameters a 5.017 and c 3.982, and a 5.003 and c 3.978 A, respectively. These compounds readily absorb hydrogen to form LaNi 5 H 6.8 and SmCo 5 H 4 [2,3].…”

mentioning

confidence: 99%

“…The latter compound is converted into SmCo 5 H 1 at 703 80oC and is completely dehydrogenated at 1903 200oC. The specific surface area of the hydrogenation products is 0.230.3 m 2 g 31 [4]. The particle size of powders prepared by the hydride dispersion procedure is several microns.…”

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confidence: 99%

“…Our previous study of reactions in the systems Ti3 NH 3 and ScFe(Ni) 2 3NH 3 [5,6] suggest that introduction of hydrogen and nitrogen into the matrix of the intermetallic compounds AB 5 would allow preparation of nitrogen-containing hydrides and, by disproportionation of the intermetallic compounds under the action of ammonia, of finely divided products: transition metal (Co or Ni) and hydrides of nitrides of metal A, in the form of homogeneous mixtures.…”

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Reactions in AB5-NH3 systems

et al. 2004

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Treatment of intermetallic compounds LaNi 5 and SmCo 5 with ammonia (initial ammonia pressure 0.630.7 MPa) in the presence of 10 wt % NH 4 Cl as an activator results in hydrogenation of these compounds or, in the case of SmCo 5 , in disproportionation to form Sm 2 Co 7 H x . In some cases, the intermetallic matrix decomposes under this treatment.Intermetallic compounds AB 5 (A = La, Sm; B = Ni, Co) are used as metal hydride accumulators of hydrogen and for production of permanent magnets [1].Intermetallic compounds LaNi 5 and SmCo 5 (structural type CaCu 5 ) have a hexagonal lattice with the parameters a 5.017 and c 3.982, and a 5.003 and c 3.978 A, respectively. These compounds readily absorb hydrogen to form LaNi 5 H 6.8 and SmCo 5 H 4 [2, 3]. After hydrogenation completion, LaNi 5 H 6.8 liberates hydrogen to form a-solid solution [2], and SmCo 5 H 4 loses hydrogen to form SmCo 5 H~2. The latter compound is converted into SmCo 5 H 1 at 703 80oC and is completely dehydrogenated at 1903 200oC. The specific surface area of the hydrogenation products is 0.230.3 m 2 g 31 [4]. The particle size of powders prepared by the hydride dispersion procedure is several microns.Our previous study of reactions in the systems Ti3 NH 3 and ScFe(Ni) 2 3NH 3 [5, 6] suggest that introduction of hydrogen and nitrogen into the matrix of the intermetallic compounds AB 5 would allow preparation of nitrogen-containing hydrides and, by disproportionation of the intermetallic compounds under the action of ammonia, of finely divided products: transition metal (Co or Ni) and hydrides of nitrides of metal A, in the form of homogeneous mixtures.In this work we studied experimentally intercalation of nitrogen and hydrogen into the lattice of intermetallic compounds AB 5 during treatment of these compounds with NH 3 at different temperatures in the presence of NH 4 Cl promoter. Reaction of LaNi 5 and SmCo 5 with ammonia (so-called hydronitriding process) was studied at the initial ammonia pressure of 0.5630.70 MPa and 1503500oC and in the presence of ammonium chloride (10 wt % with respect to the amount of the intermetallic compound).As determined by X-ray diffraction, LaNi 5 is a single-phase compound with the lattice constants, a 5.013 and c 3.986 A (CaCu 5 structure); SmCo 5 (CaCu 5 structure, a 5.001 and c 3.971 A) contains a minor amount of Sm 2 Co 7 located in the intergranular space and promoting cracking and crushing of the SmCo 5 sample in the course of its hydrogenation.The conditions of reactions of NaNi 5 and SmCo 5 with ammonia and composition, lattice constants and specific surface area of the reaction products are summarized in the table. As seen from the table, the reaction of LaNi 5 and SmCo 5 with ammonia at 150oC (sample no. 1 and 8) for 25 h yields a solid solution of hydrogen in the AB 5 matrix. As a result, the lattice constants of the intermetallic compounds slightly increase: a 5.015 and c 3.990 A for La 5 Ni 5 H 0.5 and a 5.001 and c 4.034 A for SmCo 5 H 0.3 . The specific surface area of La 5 Ni 5 H 0.5 (1.3 m 2 g 31 ) ...

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confidence: 62%

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confidence: 99%

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confidence: 99%

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“…This work continues a series of studies on preparation of high-melting metal and intermetallic compounds as finely dispersed or nanometer-size powders by the reaction with ammonia [6,7]. Here we report on the transformations of SmFe 11 Ti in ammonia at various temperatures in the presence of ammonium chloride as reaction activator.…”

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Reaction of the Intermetallic Compound SmFe11Ti with Gaseous Ammonia

et al. 2005

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The reaction of the intermetallic compound SmFe 11 Ti with ammonia at the initial NH 3 pressure of 0.6 3 0.8 MPa in the temperature range 150 3 450oC in the presence of 10 wt % NH 4 Cl as activator was studied. Depending on the reaction temperature, SmFe 11 Ti undergoes both hydrogenation to form a hydride phase of the starting intermetallic compound and disproportionation to form a hydride phase of a new intermetallic compound. The reaction products are finely dispersed powders. The magnetic properties of the products were studied.

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XPS and AES Study of Oxygen Interaction on the Surface of the ZrNi Intermetallic Compound

Roustila

Rabehi

Souici

et al. 2012

AMR

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ZrNi intermetallic compound is used in several application fields due to its very favorable characteristics for the storage of hydrogen. The hydrogen reactions are important, it is vital to examine the evolution of physico-chemical properties at the surface. X-ray photoelectron spectroscopy, is used to follow the evolution of electronic properties of ZrNi versus the ion sputtering in ultra high vacuum in the range 300-600°C. Morever, the evolution of species concentrations at the surface of ZrNi in the range 100-700°C is followed by means of Auger electron spectroscopy. The present results show that temperature and ion sputtering favor significant changes in surface properties of ZrNi. In situ annealing of ZrNi favors the oxygen decontamination associated with segregation of zirconium metal on the surface. The values of binding energies deduced from the reconstruction of XPS spectra, allowed the identification of species present at the surface. The results indicate that nickel is not contaminated and all the obtained sub-oxides are related to bonding states of oxygen with zirconium (Zr2O, ZrO, ZrO2and Zr2O3). The ion sputtering of the surface of ZrNi causes preferential sputtering phenomenon. The later results from the removal of surface layers and from the appearance of zirconium oxide layers initially present on the surface. The results obtained by AES show the segregation of impurities (oxygen and carbon) and of zirconium on the surface of ZrNi. AES observations of Zr segregation start to be important above 300°C and this is in agreement with XPS analysis showing a Zr enrichment of the surface of ZrNi.

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Cited by 4 publications

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Reactions in AB5-NH3 systems

Reactions in AB5-NH3 systems

Reaction of the Intermetallic Compound SmFe11Ti with Gaseous Ammonia

XPS and AES Study of Oxygen Interaction on the Surface of the ZrNi Intermetallic Compound

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