Synthesis of fcc Mg–Ti–H alloys by high energy ball milling: Structure and electrochemical hydrogen storage properties

Mg–Ti–H alloys were synthesized by high energy ball milling from equimolar mixtures of MgH2 + TiH2, MgH2 + Ti and Mg + TiH2 in the presence of 10 wt.% Pd. X-ray diffraction analyses combined with Rietveld refinement revealed that after 60 h of milling, all as-milled Mg–Ti–H alloys are made of two face-centered-cubic (fcc) phases, with lattice parameters ∼4.47 and ∼4.25 Å, in different proportions depending on the composition of the initial mixture. The Mg–Ti–H alloys displayed a similar electrochemical behavior, i.e. their hydrogen discharge capacity was highest during the first cycle and then decreased rapidly with cycling. The maximum discharge capacities of the 60 h-milled MgH2 + TiH2, MgH2 + Ti and Mg + TiH2 materials were 300, 443 and 454 mAh g−1, respectively. No apparent correlation could be established between the maximum discharge capacity of the Mg–Ti–H materials and the two fcc phase proportion.