The phase transformations of Mg 1.4Pr 0.6Ni 4 and Mg 1.0Pr 1.0Ni 4 during hydrogenation and dehydrogenation were investigated using in situ X-ray diffraction (XRD). Both alloys showed the cubic MgCu 4Sn type structure with space group F4̄3m before hydrogenation. The hydride β-Mg 1.4Pr 0.6Ni 4H ∼3.6 had the same crystal structure as the starting alloy, and its lattice was expanded by 4.3% by hydrogenation. Mg 1.0Pr 1.0Ni 4 was initially transformed to an orthorhombic β-Mg 1.0Pr 1.0Ni 4H ∼4 with space group Pmn2 1. By further hydrogenation, the orthorhombic hydride changed to β-Mg 1.0Pr 1.0Ni 4H ∼6 with a cubic structure with space group F4̄3m. The lattice constant of β-Mg 1.0Pr 1.0Ni 4H ∼6 was 7.6% larger than that of the starting alloy. Through dehydrogenation, all hydride phases returned to the alloy phase without any amorphization or disproportionation.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films