Local bonding structure in mechanically activated TiH2 and TiH2Â +Â graphite mixture

The local bonding structure of mechanically activated TiH2 and TiH2/graphite mixture is studied by means of temperature-programmed desorption (TPD), X-ray emission- and absorption-spectroscopy. Ball milling of TiH2 in the presence of graphite results in a modification of the hydrogen occupation sites. Additional TiC bonds from chemical bonding of Ti with carbon, which occupies octahedral interstitials, appears in TiH2 due to intimate contact between graphite and TiH2 nanoparticles embedded into an amorphous graphite matrix. Mixed configurations around Ti atoms with proportional combination of local TiH and TiC bonds significantly decrease the thermal stability of TiH2.