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The title compounds are prepared by mechanical alloying of YM4 (M: Co, Ni, Cu; obtained by arc melting of the elements) and Mg powder followed by annealing under argon (Ta containers, 600—800 °C, 8 h).

The title compounds are prepared by mechanical alloying of Mg with stoichiometric amounts CeCo4 or Ce2Co9 (obtained by arc-melting in Ar) followed by annealing at 800 °C for 7 h under 1 bar argon.

The intermetallic compound Zr6FeAl2 was hydrogenated (deuterated) at room temperature and investigated by X-ray and neutron powder diffraction. The hydride (deuteride) crystallizes with hexagonal symmetry (space group P62c; deuteride: a = 8.1354(4) A, c = 7.0940(6) A, V = 406.62(5) A3, Z = 2, refined composition Zr6FeAl2D9.82(3)). Its metal atom substructure derives from an ordered Fe2P type host structure (space group P62m) by small atomic displacements that lead to a doubling of the c axis. Deuterium occupies two types of tetrahedral [Zr4], one type of tetrahedral [Zr3Fe] and one type of trigonal bipyramidal [Zr3Fe2] interstices, thus avoiding the neighbourhood of aluminium. The metal-deuterium bond distances are in the range Zr-D = 2.03–2.22 A and Fe-D = 1.73–1.77 A, while the shortest Al-D distance is 2.90 A. The hydrogen sorption properties of Zr6FeAl2 are intermediate to those of Zr2Fe and Zr2Al.

Hydrogen absorption and desorption properties of the (Hf,Zr) 2 Fe quasibinary alloys (Ti 2 Ni structure type) and the oxygen-stabilised compound Zr 4 Fe 2 O 0.6 with the filled-Ti 2 Ni type of structure, have been studied and discussed in relation to their phase-structural and chemical composition. The crystallographic characteristics, hyperfine parameters and magnetic properties of the hydrogenated alloys have been determined.

Hydrogen storage capacity and crystal structure of hydrogen-free Zr3V3O0.6 and its saturated deuteride, Zr3V3OxD9.6, have been studied using both X-ray and neutron powder diffraction. Experimental data together with the geometrical analysis of the crystal structure of the deuteride indicate that oxygen non-stoichiometry plays a significant role in the 2-fold increase of hydrogen storage capacity of Zr3V3O0.6 compared with the stoichiometric oxygenated Zr3V3O.