XPS study of hydrogen and oxygen interactions on the surface of the NiZr intermetallic compound

0Citations
Citations of this article
2Readers
Mendeley users who have this article in their library.

Abstract

The cathodic discharge of hydrogen on the surface of massive specimens of NiZr intermetallic compound readily form the trihydride NiZrH3 which exhibit the same crystallographic parameters as the trihydride obtained by gas phase charging. Moreover microstructural studies of the first stage of the hydriding process during cathodic charging of massive samples allow to follow the influence of the microstructure of NiZr on the germination of cracks and on the first stage of the decrepitation associated with H absorption. The effect of microstructure on delayed cracking phenomena associated with the hydride partial decomposition at room temperature can also be observed after interruption of the cathodic discharge. These results show that the NiZr microstructure could strongly affect both the hydriding kinetic, the hydride stability and further the amount of hydrogen stored in the intermetallic compound. The XPS analysis of the surface of NiZr after cathodic charging shows the coexistence of zirconium core levels characteristic of Zr-H and Zr-O bounds. The hydrogen absorption affects the electronic properties of Zr atoms in the intermetallic compound in a similar way of what is observed in pure Zr: a H-induced band is observed about 6 eV below the Fermi level together with a chemical shift of the Zr core levels characteristic of the hydride formation. The presence of oxygen on the surface decreases the intensity of the Ni2p core levels whereas the desappearence of the satellit located at 5 eV (below Ni 2p) is associated with a H-induced filling of the 3d band of Ni atoms in NiZr. In situ exposure of the specimen surface to hydrogen gas at room temperature allows to partially reduce the oxide film leading to the presence of an zirconium hydroxide. The cosegregation on the surface of oxygen and zirconium is clearly evidenced by XPS in the 20 to 380°C temperature range. A preferential Zr enrichment of the surface is observed at higher temperature; the occupancy fraction of the surface sites by Zr atoms is as large as 98% at 600°C. This is presumably a consequence of both the oxygen dissolution in NiZr and a preferential segregation of Zr atoms on the surface.

Cite

CITATION STYLE

APA

Roustila, A., Chêne, J., & Séverac, C. (2006). XPS study of hydrogen and oxygen interactions on the surface of the NiZr intermetallic compound. In 16th World Hydrogen Energy Conference 2006, WHEC 2006 (Vol. 3, pp. 2605–2615).

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free