NMR to determine rates of motion and structures in metal-hydrides

Measurements of nuclear magnetic resonance (NMR) relaxation times allow the rates of H and D atomic hopping in metal-hydrides to be determined. A first example compares the rates of H hopping in Mg_(65)Sc_(35)Pd_(2.4)H_(220), a promising new battery electrode and storage alloy, to LaNi_5H_x and to the end-members of the alloy system, ScH_2 and MgH_2. The motion of MgScH is more rapid than in the metallic ScH_2 and the ionic MgH_2, but slower than in LaNi_5H_x. Magic-angle spinning (MAS) NMR of metal-deuterides is a newer method that can resolve inequivalent D atoms and measure the rate of diffusive exchange between the sites. Examples include the tetrahedral and octahedral sites in YD_(2+x) and D in ZrNiD_x