Investigation of diffusion processes in liquid sodium and sodium-hydrogen melt by quasielastic neutron scattering

The quasielastic neutron scattering experiments on liquid sodium (at $T= 378$, $573$, and $693$ K) and sodium-hydrogen melt ($T = 693\,$K, hydrogen concentration ${\sim}\,0.4\%$ at.) were performed with the DIN-2PI time-of- flight spectrometer. The characteristics of the diffusion mobility for particles comprising the liquids studied are extracted from the experimental results and analyzed with the help of the phenomenological and “relaxing cage” models. The self-diffusion coefficient in liquid sodium obtained for all temperatures is in the agreement with the values known from literature. The diffusion mobility in pure sodium and in sodium–hydrogen melt were found to be coinciding; it leads to the conclusion that in our experimental conditions hydrogen exists and diffuses in melt in the form of hydride NaH.