Structure and hydrogenation study of nickel substituted NdCo3NiB

Jean-Philippe Soulié (1) , Nicolas Penin (2) , Klaus Yvon (3)

1 Ilika Technologies Ltd.
2 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
3 Laboratory of Crystallography

In an attempt to observe hydrogen (deuterium) induced atomic ordering of transition (T) metals in AB5-type derivative structures neutron diffraction and hydrogen cycling experiments were performed on a nickelsubstituted boride sample of composition NdCo3NiB. While uncycled NdCo3NiB crystallizes with the centrosymmetric CeCo4B-type structure (space group P6/mmm), hydrogenation (deuteration) and cycling of NdCo3NiB at 373 K between 0 and 60 bar hydrogen (deuterium) atmosphere induces a symmetry decrease to non-centrosymmetric space group P6mm. Evidence for partial cobalt/nickel ordering is found in pristine NdCo3NiB but not in its deuteride NdCo3NiBDx. Compared to boron free AB5-type compounds deuterium occupies only those interstices that have no boron atom in their coordination sphere. These findings are consistent with repulsive B-D interactions. At 303 K the hydrogen equilibrium plateau pressure of the NdCo3NiB-H system is about 2 bar, and the hydrogen content at 10 bar is about 3.1 H atoms per formula unit.

Mots clés: Rare earth alloys; Hydrogen storage materials; Crystal structure; Neutron diffraction

Domaines: Matériaux

Jean-Philippe Soulié, Nicolas Penin, Klaus Yvon. Structure and hydrogenation study of nickel substituted NdCo3NiB. Journal of Alloys and Compounds, 2012, 526, pp.63-67. ⟨10.1016/j.jallcom.2012.02.107⟩. ⟨hal-00688060⟩