Hydrogen ordering inα-LuDxinvestigated by diffuse neutron scattering

Hydrogen ordering in the solid-solution phase of ${\mathrm{LuD}}_{\mathrm{x}}$ is investigated by diffuse-neutron-scattering techniques. The results show a linear ordering tendency of hydrogen atoms forming chains along the hexagonal c direction. Within the chains, second-neighbor tetrahedral sites are occupied. The scattering pattern in both the $c^{\mathrm{*}}$-$a^{\mathrm{*}}$ and $c^{\mathrm{*}}$-$b^{\mathrm{*}}$ reciprocal-lattice planes gives evidence for interchain correlations.