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Nanomateriały dla energetyki i ochrony klimatu

Okońska I., Foltynowicz Z.

Czysta Energia

2012

Nr 3

26-27

Surface segregation effect in nanocrystalline Mg-Ni alloys and composites

Smardz K., Smardz L., Okońska I., Jurczyk M.

Materials Science Poland

2007

Vol. 25, No. 2

423--428

X-ray photoelectron spectroscopy studies showed that the surface segregation of Mg atoms and width of the valence band in the nanocrystalline Mg2Ni alloy are greater compared to those observed in polycrystalline Mg2Ni thin films. Especially, a strong surface segregation of Mg atoms was observed for the Mg2Ni/Pd composites. In this case, Mg atoms strongly segregate to the surface and form an Mg-based oxide layer under atmospheric conditions. The lower lying Ni and Pd atoms form a metallic subsurface layer and could be responsible for the observed, relatively high hydrogenation rate. Furthermore, the valence band broadening observed in the nanocrystalline Mg2Ni alloys and Mg2Ni/Pd composites could also significantly influence their hydrogenation properties.

Electronic and electrochemical properties of Mg2Ni alloy doped by Pd atoms

Szajek A., Okońska I., Jurczyk M.

Materials Science Poland

2007

Vol. 25, No. 4

1251--1257

The structure and electrochemical properties of nanocrystalline Mg2Ni and Mg2Ni/Pd nanocomposite have been studied. The materials were prepared by mechanical alloying. In nanocrystalline Mg2Ni powder, discharge capacities up to 100 mAźhźg-1 were measured. It was found that mechanically coated Mgbased alloys with palladium have effectively reduced the degradation rate of the studied electrode materials. Finally, the properties of nanocrystalline alloys and their nanocomposites were compared to those of microcrystalline samples. The electronic structure was studied by ab initio calculations, which showed that the 3b positions in the unit cell are preferred by the Pd impurities.