The crystal structures of EuH2 and EuLiH3 by neutron powder diffraction

EuH2 has been prepared by solid-gas and EuLiH3 by solid-solid reaction. The ir structures have been investigated by neutron powder diffraction on the d euterides at a wavelength close to the minimum of the neutron absorption cr oss-section of a natural isotope mixture of europium. EuD2 crystallises wit h the orthorhombic PbCl2-type structure (space group Pnma, a=623.9(2), b=37 9.6(1), c=719.6(2) pm, Z=4). and EuLiD3 with the cubic inverse perovskite t ype structure (space group Pm (3) over bar m, a=378.75(5) pm, Z=1). Both de uterides are characterised by divalent europium and fully occupied deuteriu m sites. The Eu-D distances in EuD2 are 255 pm (average over 9-fold Eu co-o rdination) and those in EuLiD3 are 268 pm (12-fold Eu co-ordination). (C) 2 000 Elsevier Science S.A. All rights reserved.