Structural characteristics and hydrogen storage properties of Ca 3.0‑ x Mg x Ni 9 ( x = 0.5, 1.0, 1.5 and 2.0) alloys
Abstract
The effect of Mg content on the structural characteristics and hydrogen storage properties of the Ca 3.0‑ x Mg x Ni 9 ( x = 0.5, 1.0, 1.5 and 2.0) alloys was investigated. The lattice parameters and unit cell volume of the PuNi 3-type (Ca, Mg)Ni 3 main phase decreased with increasing Mg content. The 6 c site of PuNi 3-type structure was occupied by both Ca and Mg atoms. Moreover, the occupation factor of Ca on the 6 c site decreased with the increase of Mg content. The hydrogen absorption capacity of the alloys decreased due to higher Mg content. However, the thermodynamic properties of hydrogen absorption and desorption were improved and the plateau pressures were increased. When x = 1.5–2.0, the Ca 3.0‑ x Mg x Ni 9 alloys had favorable enthalpy (Δ H) and entropy (Δ S) of hydride formation.
- Publication:
-
International Journal of Hydrogen Energy
- Pub Date:
- January 2009
- DOI:
- 10.1016/j.ijhydene.2008.11.051
- Bibcode:
- 2009IJHE...34.1483S
- Keywords:
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- Hydrogen storage alloy;
- Phase structure;
- Hydrogen storage property;
- Thermodynamic behavior