Synthesis and structural study of Ti-rich Mg–Ti hydrides

MgxTi1−x (x=0.15, 0.25, 0.35) alloys were synthesized by means of ball milling. Under a hydrogen pressure of 8MPa at 423K these Mg–Ti alloys formed a hydride phase with a face centered cubic (FCC) structure. The hydride for x=0.25 consisted of single Mg0.25Ti0.75H1.62 FCC phase but TiH2 and MgH2 phases were also formed in the hydrides for x=0.15 and 0.35, respectively. X-ray diffraction patterns and the atomic pair distribution function indicated that numbers of stacking faults were introduced. There was no sign of segregation between Mg and Ti in Mg0.25Ti0.75H1.62. Electronic structure of Mg0.25Ti0.75H1.62 was different from those of MgH2 and TiH2, which was demonstrated by 1H nuclear magnetic resonance. This strongly suggested that stable Mg–Ti hydride phase was formed in the metal composition of Mg0.25Ti0.75 without disproportion into MgH2 and TiH2.