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

Abstract

Nuclear magnetic resonance (NMR) has been used to determine the activation energies for hydrogen diffusion in ZrH1.75, ZrH1.96, Zircaloy-2-H1.90 and Zr0.67Rh0.33H0.95. The proton spin-lattice relaxation time, T1, was determined at a frequency of 60.15 MHz as a function of temperature over the range 200-900K. For ZrH1.75 the minimum value of T1 was found to occur at 680K whereas for the others the T1 minima all occurred at 850K. The activation energies found were 0.55 eV for ZrH1.75, 0.80 eV for ZrH1.96, 0.86 eV for Zircaloy-2-H1.90 and 0.80 eV for Zr0.67Rh0.33H0.95 from the T1 data near the T1 minima. Using the low-temperature T1 data, where the relaxation rate due to diffusion could be neglected, values of the electronic contribution to the spin-lattice relaxation time (T1e) were obtained. The quantity (G1eT)-1/2 was found to increase with temperature, T, over the range 200-500K.