The Hydrogenation of M Ni ₃ Compounds ( M = Si, Ge, Sn, Sb, Zr, V, Fe)

The hydrogenation properties of nickel‐rich M Ni 3 compounds with M being a transition metal ( M = Zr, V, Fe) or a p‐block element ( M = Si, Ge, Sn, Sb) were studied using differential scanning calorimetry (DSC) under up to 7 MPa hydrogen pressure and temperatures up to 723 K and by X‐ray powder diffraction (XRPD). M Ni 3 ( M = Zr, Si, Sb) compounds do not show a reaction toward hydrogen. For M Ni 3 ( M = V, Fe, Ge) compounds, only a very small hydrogen‐induced volume increase of the unit cell occurs, while this is considerable for Ni 3 Sn. Hydrogen filling of voids in the parent intermetallic hexagonal Ni 3 Sn (Ni 3 Sn type, P 6 3 / mmc , a = 529.092(3) pm, c = 424.382(3) pm) leads to a 0.9% increase in unit cell volume and the formation of α‐Ni 3 SnH x (filled Ni 3 Sn type, P 6 3 / mmc , a = 529.415(4) pm, c = 427.629(3) pm). This is followed by a transition to the cubic AuCu 3 type β‐Ni 3 SnH y (filled AuCu 3 type, , a = 373.270(2) pm) with further hydrogen uptake as evident by a further increasing unit cell volume per formula unit (1.1% with respect to pristine Ni 3 Sn).