| Abstract |
| Samples with a composition of 80 wt% Mg-14 wt% Ni-6 wt% NbF5 (denoted as Mg-14Ni-6NbF5) were prepared by reactive mechanical grinding, and the hydriding and dehydriding properties of the specimens were then examined. The activation of Mg-14Ni-6NbF5 was completed after two hydriding (under 12 bar H2)-dehydriding (in vacuum) cycles. Mg-14Ni-6NbF5 had a hydrogen storage capacity of about 5.5 wt% H. At the number of cycles n = 2, the sample absorbed 4.93 wt% H for 5 min, 5.20 wt% H for 10 min, and 5.48 wt% H for 60 min at 573 K under 12 bar H2, and desorbed 0.58 wt% H for 10 min, 1.52 wt% H for 30 min, and 2.47 wt% H for 60 min at 573 K under 1.0 bar H2. The hydriding rate increased as the temperature increased from 423 Kto 573 K since the effect of acceleration of thermally activated process predominates, and decreased from 573 K to 623 K since the effect of decrease in the driving force for the hydriding reaction predominates. NbF5 formed MgF2 and NbH2 by the reaction with Mg and hydrogen. Mg-14Ni-6NbF5 exhibited a higher hydriding rate than both Mg-10NbF5 and Mg-14Ni-6Fe2O3. |
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| Key Words |
| hydrogen absorbing materials, mechanical alloying/milling, scanning electron microscopy, X-ray diffraction, Ni and NbF5 addition |
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