Nuclear magnetic relaxation and diffusion of hydrogen in an amorphous Ni-Ti alloy

Abstract

The nuclear magnetic relaxation rate of 1H in a-Ni35Ti65 has been measured. The rate may be accounted for by the nuclear dipole-dipole interaction of the diffusing spins together with a second relaxation path through the hyperfine coupling to the electron bands. It is found that the dipolar part of the relaxation may be interpreted by Torrey's model from which an activation energy of the diffusion equal to 0.26 eV may be deduced. Since the view has often been expressed that a distribution of activation energies in amorphous materials will lead to departures from this model, the relaxation rate has also been calculated from a computer simulation of diffusion on a random array. Deviations from the model were discovered but they were not large enough to warrant re-interpretation of the present experiment.