Nuclear-Magnetic-Resonance Investigation of Proton Motion in Scandium Hydride

Hydrogen diffusion processes in nonstoichiometric scandium hydrides have been investigated using transient nuclear-magnetic-resonance methods. Activation energies ($E_A$) were found to be strongly concentration dependent with two processes becoming evident as the hydrogen-to-metal ratio ($x$) approached 2. The variation of $E_A$ with $x$ is interpreted as an effect of non-rigid-band behavior for the electron states. Both relaxation-time analysis and rigid-lattice linewidths suggest appreciable occupation of octahedral sites normally vacant in other dihydrides.