Surface effects and the formation of metal hydrides

Cu Precipitations at the Surface of Crystalline Cu — Zr Alloys after Annealing in Hydrogen*

“…Amorphous and also crystalline alloys of Cu with the d-transition metals Zr, Ni and Pd have been studied quite intensively for the last few years among other reasons because of their special dynamical and diffusional properties in the bulk and at the surface which results in interesting catalytic and hydrogen sorption phenomena [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

“…Whereas surface segregation effects induced by oxygen are known to be strong and important e.g. for bimetallic catalyst, activation of hydrogen storage materials and getters [9,[11][12][13], surface effects induced by the adsorption or absorption of hydrogen are usually rather weak or absent [12,13,14]. In the case of Cu-d transition metal alloys, however, the results on hydrogen induced surface phenomena are rather controversial [14].…”

The kinetics of Cr layer coated on TiNi films for hydrogen absorption

“…Since the initial hydride formation raises the temperature and as a result of expansion of the metallic lattice, the surface layer cracks due to this reaction speed-up. The hydrogenation disintegrates the host metal, a fresh surface is produced and the reaction is further accelerated [15]. But at higher temperature the reaction of hydrogen with a metal is usually an exothermic process.…”

XPS Valence band and segregation effect in nanocrystalline Mg2NiMg2Ni-type materials

“…The lanthanum atoms binds the impurities as oxide or hydroxide and keeps the Ni metallic, which then is able to split the hydrogen molecule [3]. Therefore, the surface segregation process of lanthanum in the presence of O 2 or H 2 O explained the excellent hydrogenation properties of LaNi 5 [3][4][5].…”