Structural, magnetic, electrochemical and hydrogen absorption properties of GdyMg2−yNi4−xAlx compounds with 0.4 < y < 2 and 0 < x < 1.2

A solid solution with the C15b structure (MgCu4Sn-type) exists as a series from GdNi2 to Gd0.4Mg1.6Ni4 (Gd0.2Mg0.8Ni2). These compounds were successfully elaborated by (i) Mechanical Alloying (MA) and (ii) melting followed by a subsequent annealing. It was also possible to synthesise the solid solution GdMgNi4−xAlx with x up to 1.2. The product is highly dependent on the elaboration route which induces a drastic change in both chemical and physical properties (i.e. magnetism, electrochemistry, and structural disorder). A direct relationship between all these property modifications was established. Finally, it is shown that different compounds have different behaviours towards hydrogen sorption regarding both the hydrogen uptake and the thermodynamic results.