R. G. Barnes

Proton magnetic resonance spectra of Y H 3 and Lu H 3

A paper published by some of the present authors showed an unexpected doublet structure in the rigid-lattice proton magnetic resonance spectra of

Hydrogen locations, diffusion and the electronic density of states in yttrium dihydrides: A nuclear magnetic resonance investigation☆

mathrm{Y}{mathrm{H}}_{3}

NMR studies of localized interstitial hydrogen motion in the h.c.p. metals Sc, Y and Lu

and

Hydrogen hopping rates and the order–disorder transitions in sub-stoichiometric lanthanum trihydride

mathrm{Lu}{mathrm{H}}_{3}

Novel measurements of nuclear spin cross-relaxation in metal hydrides

. In the present study accurate spectra which contain no doublet features are obtained for

NMR studies of diffusion anisotropy in metal hydride single crystals

mathrm{Y}{mathrm{H}}_{2.96}

Electron density-of-states and the metal–insulator transition in LaHx

and

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

mathrm{Lu}{mathrm{H}}_{3}

Evidence for independent motional processes on the two interstitial sublattices of a layer-structured metal hydride: hydrogen spin-lattice relaxation and motional narrowing in zirconium monohalide hemihydrides, ZrXH/sub 0. 5/

using the technique of magic echoes. It is shown that the original spectra were distorted by time shifting of the time-domain data. The applicability of using magic echoes with these two systems is justified theoretically and by comparison to free induction decays. The measured second moments of the present spectra agree well with values predicted by the Van Vleck formula, demonstrating that the broadening of the present spectra is almost entirely dipolar.

Nuclear relaxation in the dideuteride of hafnium and titanium

Abstract We report results of wide-line and pulsed proton magnetic resonance measurements on yttrium dihydrides, YH x (1.63 ⩽ x ⩽ 1.98), covering the temperature range 140–760 K and yielding information on hydrogen locations, diffusion and the density of states in the dihydride phase. Our principal conclusions are as follows. (1) At x = 1.98, wide-line second moment measurements indicate that 15% of the octahedral (O) sites in the f.c.c. CaF 2 structure are occupied by hydrogen. (2) Spin-lattice relaxation time measurements in the rotating frame ( T 1 ρ versus T ) yield hydrogen jump frequencies ν j showing three distinct regions in which the activation energy E act for hydrogen diffusion increases with T . (3) For x = 1.98 ν j is consistently higher than for x = 1.92, corroborating the partial occupation of O sites for x values below 2.0. (4) At the lower limiting composition ( x ≈ 1.8) E act becomes anomalously large (approximately 1.1 eV atom −1 ), compared with the value 0.5 eV atom −1 at x = 1.92, and the diffusion rate is about 10 3 times smaller. (5) At low temperatures the spin-lattice relaxation rate T −1 1 is dominated by the conduction electron contribution T −1 1 e . The quantity (T 1e T) −1 2 which is proportional to the density of states at the Fermi level, is 0.061 ± 0.002 s −1 2 K −1 2 for the dihydride compositions studied, indicating a constant density of states in the dihydride phase.