Zeolitic Intermetallics: LnNiSi (Ln = La–Nd)

LnNiSi (Ln = La–Nd)
comprising a three-dimensional NiSi
framework has electrons in the crystallographic cavity space. In the
temperature region 473–773 K, it accepts the insertion/de-insertion
of hydrogen topotactically without a change in unitcell volume. The
insertion of hydrogens into the cavity space is accompanied by a redox
reaction with the orbitals of atoms constituting the cavity wall.
Having small work functions, such intermetallic electrides exhibit
metallic electrical and magnetic properties. Owing to a high electron-donating
power and reversible exchange between hydrogen and the electrons,
Ru5wt%-loaded LaNiSi powder worked as an efficient catalyst for ammonia
synthesis under ambient pressure.