Electronic structure of Ni and Mo silicides investigated by x-ray emission spectroscopy and density functional theory

Jarrige, Ignace; Capron, Nathalie; Jonnard, Philippe

doi:10.1103/physrevb.79.035117

Cited by 17 publications

(7 citation statements)

References 51 publications

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“…From these calculations, we can affirm that, within our sensitivity, the possible formation of the MgCo 2 compound at the interfaces of the CoMg_1 and CoMgB 4 C_1 samples is not confirmed by XES. From comparison with transition metal silicides, the same kind of narrow bandwidth spectrum is expected for other possible Co−Mg compounds that could form out of equilibrium: CoMg , or CoMg 2 . , …”

Section: Resultsmentioning

confidence: 66%

Development and Interfacial Characterization of Co/Mg Periodic Multilayers for the EUV Range

Guen

André

et al. 2010

J. Phys. Chem. C

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Reprinted with permission from (J. Phys. Chem. C, 2010, 114 (14), pp 6484-6490). Copyright (2010) American Chemical Society.International audienceWe propose a new system, namely the periodic Co/Mg multilayer system, for optics applications in the EUV range. Close to the Mg L edge, i.e., around a wavelength of 25 nm or a photon energy of 50 eV, a reflectivity of about 43% is measured at 45° for s-polarized radiation. Moreover, it appears that this system is stable over a period of time of three months. The introduction of thin boron carbide interfacial layers proves disastrous contrary to simulations that show this could be beneficial. We combine X-ray reflectivity in the hard X-ray range, X-ray emission spectroscopy, and nuclear magnetic resonance to determine the thickness and roughness of the Co and Mg layers as well as the chemical state of the Co and Mg atoms at the interfaces. This reveals that in the Co/Mg system the interfaces are abrupt and there is no interdiffusion between the Co and Mg layers. Then the difference between the experimental and simulated reflectivities is ascribed to the interfacial roughness of the order of 0.4 nm. In the Co/Mg/B4C system, evidence of a large mixing of the Co and B4C layers is presented and explains the poor reflectance of this system

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Section: Resultsmentioning

confidence: 66%

Development and Interfacial Characterization of Co/Mg Periodic Multilayers for the EUV Range

Guen

André

et al. 2010

J. Phys. Chem. C

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“…This leads to changes in the energy of the electron shells. It is worth pointing out that bonding in Ni–Si systems can be understood in terms of hybridization of Si p states and Ni d states, with the Si s states not participating in the bonding (see e.g., Jarrige et al, 2009).…”

Section: Resultsmentioning

confidence: 99%

Electron Probe Microanalysis of Ni Silicides Using Ni-L X-Ray Lines

et al. 2016

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We report electron probe microanalysis measurements on nickel silicides, Ni5Si2, Ni2Si, Ni3Si2, and NiSi, which were done in order to investigate anomalies that affect the analysis of such materials by using the Ni L3-M4,5 line (Lα). Possible sources of systematic discrepancies between experimental data and theoretical predictions of Ni L3-M4,5 k-ratios are examined, and special attention is paid to dependence of the Ni L3-M4,5 k-ratios on mass-attenuation coefficients and partial fluorescence yields. Self-absorption X-ray spectra and empirical mass-attenuation coefficients were obtained for the considered materials from X-ray emission spectra and relative X-ray intensity measurements, respectively. It is shown that calculated k-ratios with empirical mass attenuation coefficients and modified partial fluorescence yields give better agreement with experimental data, except at very low accelerating voltages. Alternatively, satisfactory agreement is also achieved by using the Ni L3-M1 line (Lℓ) instead of the Ni L3-M4,5 line.

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“…This phenomenon may be ascribed to the electronic structure of Ni 2 Si and the crystal structure of NiSi 2 . Jarrige et al reported that the d states in Ni 2 Si had a stronger Ni metal-like character . The magnetism of NiSi was found to be nonferromagnetic from first-principles study and experimental findings .…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Catalytic Properties for Phenylacetylene Hydrogenation of Silicide Modified Nickel Catalysts

et al. 2010

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Interstitial silicide-modified nickel, with high selectivity in some hydrogenation reactions, had been produced by dissolving silicon atoms into the nickel lattices. The metallic nickel was obtained by reducing the as-prepared high surface area NiO, followed by modification of the bulk nickel through silification of silane/H2 at relatively low temperature and atmospheric pressure. The as-prepared materials were characterized by X-ray diffraction, magnetic measurements, X-ray photoelectron spectroscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and temperature-programmed reduction. The results show nickel silicide formation involves the following sequence as a function of increasing temperature: Ni (cubic) → Ni2Si (orthorhombic) → NiSi (orthorhombic) → NiSi2 (cubic). The insertion of Si atoms into the interstitial sites between Ni atoms resulted in a significant change in the unit cell lattice of nickel. All of the silicide-modified nickel materials were ferromagnetic at room temperature, and saturation magnetization values drastically decreased when Si is present. Silicide-modified nickel develops a thin silicon oxide layer during exposure to air, which can be removed by H2-temperature programmed reduction. The as-prepared bulk silicide-modified nickel showed above 92% styrene selectivity in the hydrogenation of phenylacetylene under 0.41 MPa H2 and at 50 °C for 5 h. In addition, only low conversions were obtained for styrene hydrogenation under the same hydrogen pressure and temperature for 50 min. These results indicate that these novel silicide-modified nickels are promising catalysts for the selective hydrogenation of unsaturated hydrocarbons.

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Electronic structure of Ni and Mo silicides investigated by x-ray emission spectroscopy and density functional theory

Cited by 17 publications

References 51 publications

Development and Interfacial Characterization of Co/Mg Periodic Multilayers for the EUV Range

Development and Interfacial Characterization of Co/Mg Periodic Multilayers for the EUV Range

Electron Probe Microanalysis of Ni Silicides Using Ni-L X-Ray Lines

Synthesis and Catalytic Properties for Phenylacetylene Hydrogenation of Silicide Modified Nickel Catalysts

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