Crystal structure of ErFe2D3.1 and ErFe2H3.1 at 450Â K

We studied crystal structure and deuterium (hydrogen) ordering in the ErFe2D3.1 and ErFe2H3.1 compounds by means of X-ray and high-resolution neutron powder diffraction at 450 K. It was found that the structure of these compounds is ascribed to the F23 space group, which is a subgroup of the Fd3m group commonly applied for the RFe2H3-type hydrides. The deuterium and hydrogen atoms partially occupy two types of the 48h sites. Analysis of the interatomic distances allows us to assume that the occupancy factors of D (H) atoms are limited by the electrostatic repulsive interaction between the D (H) atoms.