Nuclear magnetic resonance study of hydrogen diffusion in zirconium and some of its alloys

Nuclear magnetic resonance (NMR) has been used to determine the activation energies for hydrogen diffusion in ZrH 1.75 , ZrH 1.96 , Zircaloy-2-H 1.90 and Zr 0.67 Rh 0.33 H 0.95 . The proton spin-lattice relaxation time, T 1 , was determined at a frequency of 60.15 MHz as a function of temperature over the range 200-900K. For ZrH 1.75 the minimum value of T 1 was found to occur at 680K whereas for the others the T 1 minima all occurred at 850K. The activation energies found were 0.55 eV for ZrH 1.75 , 0.80 eV for ZrH 1.96 , 0.86 eV for Zircaloy-2-H 1.90 and 0.80 eV for Zr 0.67 Rh 0.33 H 0.95 from the T 1 data near the T 1 minima. Using the low-temperature T 1 data, where the relaxation rate due to diffusion could be neglected, values of the electronic contribution to the spin-lattice relaxation time (T 1e ) were obtained. The quantity (G 1e T) -1/2 was found to increase with temperature, T, over the range 200-500K.