Quasielastic Neutron Scattering on Complex Borohydrides

Complex Borohydrides are a class of materials of high interest, due to their possible applications in hydrogen storage in light weight vehicles. Unfortunately, the harsh conditions for (de-)hydrogenation and the sluggish kinetics make these materials not ready yet for industrial applications. Among destabilizations and structural studies, fundamental studies on hydrogen dynamics are essential. Quasielastic neutron scattering (QENS) studies on lithium and magnesium borohydrides (in different crystal phases and mixtures) will be presented, in order to explore the dynamics on the picosecond time scale. The localized reorientational dynamics of the [BH₄]^– units will be presented, as well as the low energy inelastic dynamics. The results show a strong difference of the hydrogen dynamics according to the different ionic character of the cations Li⁺ and Mg²⁺.