Relevance of hydrogen storage properties of ANi_3 intermetallics (A = La, Ce, Y) to the ANi_2 subunits in their crystal structures

摘要

To understand the fundamental reason for the poor stability in hydrogen storage, the cycling behavior of ANi_3 intermetallics (A = La, Ce, Y) under hydrogen was systematically investigated and compared with the stability of the corresponding ANi_2 intermetallics. All cycled ANi_3 intermetallics are subject to amorphization to some extent, similar to corresponding ANi_2 intermetallics. Since the crystal structure of ANi_3 intermetallics consists of an alternating stacking between the ANi_5 subunit and the ANi_2 subunit, the hydrogen-induced amorphization as observed in ANi_3 intermetallics is assumed to associate with the ANi_2 subunits in their crystal structures. This assumption is supported by the experimental results obtained in the present work.