Theoretical investigation of Fe substitution for Mn in complex hydride YMn2H6

Complex hydride YMn2H6 with a space group Fm3¯m has two sorts of Mn, in which one presents as a divalent cation Mn2+ on the 8c site and the other forms a complex anion [MnH6]5− on the 4a site. We investigate the stabilities of Fe substitutions for a part of Mn atoms on either the site using first-principles calculations. Our results reveal that an Fe atom prefers the 4a occupation, and the origin of this site preference can be understood by the balance of two competing energy gains brought by the 3d bands for either the 4a or 8c site substituted Fe.