XPS study of the chemisorption induced surface segregation in LaNi5 and ThNi5
- 1 January 1981
- journal article
- Published by EDP Sciences in Journal de Physique
- Vol. 42 (7), 1025-1028
- https://doi.org/10.1051/jphys:019810042070102500
Abstract
Surface segregation with the disproportionation into La and Th oxide plus precipitations of elemental Ni play an important role in the understanding of the easy hydrogen absorption of LaNi5 and of the catalytic properties of ThNi5. By means of core-level X-ray photoelectron spectroscopy we show that the chemisorption of O2, H2O, and H2 on LaNi 5 surfaces induces a strong, weak and no surface segregation, resp. Precoverage with SO2 blocks further segregation, whereas exposure to H2S does not. The oxygen induced segregation of ThNi5 at room temperature is much weaker than in LaNi5, but is very extensive at 200 °CKeywords
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