Studies of Hydrogen atom configurations in selected metal hydrides in view of repulsive interactions

The main objective of the present thesis was to gain more insight into the nature of H–H separations in transition metal based metal hydrides in view of H atom configurations and repulsive H–H interactions. In some metallic hydrides anomalies with respect to typically used geometrical criteria (Switendick rule about minimum hydrogen atom separation (not less than 2.1 Å) and Westlake rule about minimum size of interstitial hole suitable for hosting hydrogen atoms (radius at least 0.4 Å)) are observed and likely to influence their sorption properties by changing the hydrogen storage capacity or/and thermal stability. The studies were partly inspired by work on metallic hydrides/deuterides revealing the directional metal-hydrogen bonding effect (e.g. CeNi3D2.8, HoNi3Dx, ErNi3Dx, Ce2Ni7D~4) and by reports on extraordinarily short D–D (H–H) contacts (1.635(8) Å for LaNiInD1.22) in deuterides/hydrides of RENiIn (RE – rare earth element). Considering the results of this work, the present thesis attempts to answer the question whether the (short) D–D (H–H) contacts in transition metal based metal hydrides were related to preferred configurations of hydrogen atoms in the lattice and if so, how