Observation of hydride mobility in the transition-metal oxide hydride LaSrCoO₃H_0.7

The mobility of hydride anions in the transition-metal oxides is investigated. Quasielastic neutron scattering (QENS) technique is used to probe diffusion of atoms and molecules in systems such as proton-conducting oxides, metal-hydride, ionic polymers, and clay minerals. QENS relies on an accurate analysis of energy-resolved spectral lines shapes that result when neutrons scatter inelastically from atoms in motion. As the transition-metal is heated under a helium atmosphere, the equilibrium is shifted towards the formation of H₂(g) as the temperature range is reached in which the H^- in the lattice becomes more mobile. It is observed that the hydride moves between sites that are partially covalently bound to the transition-metal cations, while the proton moves between sites bound to oxide anions. Result shows that the state of hydrogen in the oxide hydride also has a degree of covalency in its interaction with neighboring ions.