Study of hydrogen self-diffusion in NbH/sub x/ using a new pulsed gradient pulsed NMR technique

A new pulsed-gradient pulsed NMR technique is presented for measuring self-diffusion in the presence of background magnetic field gradients vector G/sub o/ which make diffusion studies by other pulsed NMR techniques impractical. The theoretical development is based upon an assumed random walk model for diffusion. Experimental verification of the validity of the proposed new technique is given. NbH/sub x/ is shown to have a distribution of background magnetic field gradients vector G/sub o/ which make the experimental determination of D impractical by other pulsed-gradient pulsed NMR techniques. The proposed new technique is used to measure D as a function of temperature and hydrogen concentration in the α and α' phases of NbH/sub x/ for 0.10 less than or equal to x less than or equal to 0.89. These data exhibit Arrhenium behavior over the temperature range studied (to approximately 3500C). Good agreement with quasi-elastic neutron scattering and Gorsky effect results by other researchers is found. A detailed description of the experimental apparatus and procedures is given as well as a description of the sample preparation techniques