Hydriding kinetics of the La1.5Ni0.5Mg17–H system prepared by hydriding combustion synthesis

An experimental investigation of the hydrogen absorption rate in the two-phase (α–β) region of La1.5Ni0.5Mg17 powder under the condition of various pressures and temperatures is presented. The results are well interpreted using the Jander diffusion model, [1−(1−ξ)1/3]2=k(T,P)t, which suggests that the rate-controlling step of hydrogen absorption in La1.5Ni0.5Mg17 is three-dimensional diffusion. An apparent activation energy for such diffusion process of 90±1 kJ/mol H2 has been obtained from the absorption data.