Nuclear magnetic resonance survey of hydrogen motion and electronic structure in α-phase (NbMo)-H alloys

Abstract

The results of a proton nuclear magnetic resonance (NMR) survey of hydrogen motion and electronic structure in the solid solution (α) phase of niobium rich Nb1−yMoyHx alloys are reported (y ⩽ 0.2, x ⩽ 0.2). Measurements of the temperature dependence of the proton spin-lattice relaxation time T1 over the range 20 ⩽ T ⩽ 800 K were analyzed to yield values of the activation energy Ea and jump attempt frequency v0 for hydrogen diffusive hopping and of the product T1eT = Ce indicative of the electronic density-of-states at the Fermi level, N(EF), where T1e is that contribution to T1. The T1vs. T behavior shows features characteristic of hydrogen in random alloys, reflecting a distribution of Ea and v0 values. At high temperatures (~ 500 K), T1 exhibits anomalous behavior, passing through a maximum and decreasing again at higher temperatures in the same manner found in the NbH and (NbV)-H systems.