NUCLEAR-MAGNETIC-RESONANCE STUDY OF THE ELECTRONIC-STRUCTURE AND HYDROGEN MOTION IN THE RANDOM BCC-TAV2-H(D) SYSTEM

Nuclear magnetic resonance measurements of the H-1, 2D and V-51 spin-lattice relaxation times and Knight shifts in the random b.c.c.-TaV2Hx(Dx) system (0.1 less-than-or-equal-to x less-than-or-equal-to 2.4) have been performed over the temperature range 11-440 K. The relaxation data are analysed to obtain the parameters of H(D) diffusion, which is governed by a distribution of activation energies. The long-range diffusion of H(D) in b.c.c.-TaV2Hx(Dx) is found to be much faster than in C15-type TaV2Hx(Dx) with comparable H(D) contents. For all the studied samples (including those with mixed isotope composition) there is a distinct isotope effect on the average activation energy: EBAR(a)D > E(a)H. The measured values of the Knight shifts and the electronic (Korringa) contributions to the spin-lattice relaxation rates indicate that the density of d-electron states at the Fermi level decreases with increasing H(D) content.