Structure and bonding configuration of hydrided ErNi3 and CeCo3

Abstract

The intermetallic compounds ErNi 3 and CeCo 3 has been hydrided at low ( ≤ 0.01 GPa) and high ( up to 0.2 GPa) hydrogen pressures. X-ray and neutron diffraction characterization has shown that the resultant hydrides have structures of the same type (PuNi 3 ) as the parent intermetallics and have a larger unit- cell volume. We have identified the positions occupied by the metal and hydrogen atoms and have determined their positional parameters. The lattice anisotropy has been shown to vary little at high hydrogen concentrations. Our results indicate that the metal-hydrogen bonds in the hydrides studied are predominantly ionic for the rare- earth metals (Er and Ce) and predominantly metallic for the transition metals (Ni and Co).