Crystal Research and Technology
Cryst. Res. Technol. 36 (2001) 1385 - Abstract -

L. Smardz, K. Smardz*, M. Nowak*, M. Jurczyk*

Institute of Molecular Physics, Polish Academy of Sciences, Poznan, Poland
*Institute of Materials Science and Engineering, Poznan University of Technology, Poznan, Poland

Structure and Electronic Properties of La(Ni,Al)5 Alloys

Nanocrystalline and polycrystalline La(Ni,Al)5 alloys were prepared by mechanical alloying (MA) followed by annealing and arc melting method, respectively. The amorphous phase of MA samples forms directly from the starting mixture of the elements, without other phase formation. Heating the MA powders at 800°C for 1 h resulted in the creation of hexagonal CaCu5-type nanocrystalline compound with mean crystallite size less than 80 nm. XPS studies showed that the shape of the valence band measured for the arc melted (polycrystalline) LaNi5 is practically the same compared to that reported earlier for the single crystalline sample. The substitution of Ni in LaNi5 by Al leads to significant modifications of the electronic structure of the polycrystalline sample. On the other hand, the XPS valence band of the MA nanocrystalline LaNi4.2Al0.8 alloy is considerably broader compared to that measured for the polycrystalline sample. The strong modifications of the electronic structure of the nanocrystalline LaNi4.2Al0.8 alloy could significantly influence on its hydrogenation properties.

Keywords: hydrogen storage materials, rare-earth compounds, xps, aes


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