title: The crystal structure of Zr2NiD4.5.
abstract: The crystal structure of Zr2NiD4.5 has been determined by a combination of synchrotron radiation powder X-ray diffraction, electron diffraction and powder neutron diffraction data. Deuterium ordering results in a triclinic supercell given by asuper=6.81560 (7), bsuper=8.85137 (9), csuper=8.88007 (10) A, alphasuper=79.8337 (8), betasuper=90.0987 (9), gammasuper=90.3634 (9) degrees, which relates to the non-super unit cell as asuper=-a, bsuper=-b-c, csuper=-b+c. The centrosymmetric and fully ordered deuterium sublattice was determined by simulated annealing and Rietveld refinement. Deuterium was found to occupy three types of tetrahedral sites: two that are coordinated by four Zr atoms and one that is coordinated by three Zr atoms and one Ni atom. All D-D distances are longer than 2 A. The feasibility of the crystal structure was supported by density functional theory calculations.
authors.affiliation: Institute for Energy Technology, PO Box 40, NO-2027 Kjeller, Norway. magnuss@ife.no
authors.forename: M H
authors.initials: MH
authors.lastname: Sørby
authors.forename: A E
authors.initials: AE
authors.lastname: Gunnaes
authors.forename: O M
authors.initials: OM
authors.lastname: Løvvik
authors.forename: H W
authors.initials: HW
authors.lastname: Brinks
authors.forename: H
authors.initials: H
authors.lastname: Fjellvåg
authors.forename: B C
authors.initials: BC
authors.lastname: Hauback