HYDROGEN IN THE A15 COMPOUNDS NB3SN AND NB3AL - A NUCLEAR-MAGNETIC-RESONANCE STUDY

Nuclear magnetic resonance measurements of the Sn-119, Al-27 Knight sh ifts and the Sn-119, Al-27 and H-1 spin-lattice relaxation rates in th e A15-type compounds Nb3SnHx(D-x) (x = 0, 0.7 and 1.2) and Nb3AlHx (x = 0, 2.3) have been performed over the temperature range 10-460K. The low temperature Sn-119 Knight shift and spin-lattice relaxation data i ndicate that in Nb3SnHx(D-x) the density of electron states at the Fer mi level decreases strongly with increasing x. The hydrogen mobility i n Nb3Al is found to be much higher than that in Nb3Sn. The behaviour o f the proton spin-lattice relaxation rate for Nb3AlH2.3 in a wide rang e of resonance frequencies (9-90 MHz) can be described by the model us ing a double-peak distribution of activation energies.