The H diffusivities in YHx were measured, by means of pulsed-field gradient nuclear magnetic resonance techniques, at up to 920K for x = 1.91 and up to 620K for x = 1.95 and 2.03. The observed values tended to be appreciably greater than those in the dihydrides of Ti and Zr. The activation enthalpy, obtained by fitting an Arrhenius expression to the diffusivities, decreased substantially with increasing x-value; from 0.53eV for x = 1.91 to 0.38eV for x = 2.03. Measurements of the proton spin-lattice relaxation were performed on the same samples. The temperature and concentration dependences of the dipolar relaxation were consistent with the pulsed-field gradient results. Besides these relaxations, the data revealed contributions that were due to very small concentrations of paramagnetic impurities which dominated the measured rates below about 500K; even at impurity levels as low as 20ppm.

Model-Independent Measurements of Hydrogen Diffusivity in the Yttrium Dihydrides. G.Majer, J.Gottwald, D.T.Peterson, R.G.Barnes: Journal of Alloys and Compounds, 2002, 330-332, 438-42