Microscopic Characteristics of H Diffusion and Diffuse Scattering of Radiations in H.C.P.-Ln-H (from the Data on Electrical-Resistivity Relaxation)

The further theoretical study of the short-range order kinetics of H-atoms at tetrahedral interstices in h.c.p. lanthanoids (Ln), for instance, lutetium (Lu), is developed. It is studied by the use of available data of measurements of residual electrical resistivity for interstitial solid solutions h.c.p.-Lu-H during the isothermal annealing. Within the framework of two models (with one and two relaxation times), the relaxation times of this process in some α-Lu−H solid solutions at temperatures 160–180 K are evaluated on a base of the available experimental results. Within the framework of the hypothesis about an identity of maximum characteristic relaxation times of diffuse radiation scattering and relaxation times of electrical resistivity, the time evolution of normalized change of radiation diffuse-scattering intensity is predicted and corresponds to the wave-vector star, which dominates in mapping a structure of the short-range order (at different quenching and annealing temperatures) for polycrystalline LuH_0,180 and LuH_0,254 solid solutions. The pre-exponential factor in the Arrhenius-type law for the relaxation time and energy of migration activation for H atoms in these solid solutions are obtained.