Effect of Ni on Mg based hydrogen storage alloy Mg3Nd

Magnesium-neodymium based alloys were prepared by induction melting in an alumina crucible under protection of pure argon atmosphere. XRD patterns show that the as-melted Mg-Nd and Mg3NdNi0.1 diffraction peaks can be excellently indexed with DO3 structure (BiF3 type, space group Fm3m). The lattice constant of Mg3Nd phase is 0.7390 nm, which is determined by XRD analysis using Cohen's extrapolation method. The reversible hydrogen storage capacity reaches 1.95wt.% for Mg3Nd and 2.68wt.% for Mg3NdNi0.1. The desorption of hydrogen takes place at 291 °C for Mg3Nd and at 250 °C for Mg3NdNi0.1. The alloys could absorb hydrogen at room temperature with rapid hydriding and dehydriding kinetics after only one cycle. The enthalpy (ΔH) and entropy (ΔS) of Mg3Nd-H dehydriding reaction were −68.2 kJ.mol−1 H2 and −0.121 kJ.(K.mol)−1 H2 determined by using van't Hoff plot according to the pressurecomposition-isotherms (P-C-I) curve measured at different temperatures. Hydrogen absorption kinetic property of Mg3NdNi0.1 alloy was also measured at room temperature.