Temperature variation of the structural parameters in actinide tetrafluorides

Journal Article · Wed Nov 30 23:00:00 EST 1994 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.467963· OSTI ID:6893174

Kern, S ^[1]; Hayward, J; Roberts, S ^[2]; Richardson, Jr, J W; Rotella, F J ^[3]; Soderholm, L ^[4]; Cort, B; Tinkle, M; West, M; Hoisington, D ^[5]; Lander, G H ^[6]

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1. Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States) Intense Pulsed Neutron Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2. Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States)
3. Intense Pulsed Neutron Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
4. Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
5. Nuclear Materials Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
6. European Commission, JRC, Institute for Transuranium Elements, Postfach 2340, D-76125 Karlsruhe (Germany)

We have used neutron diffraction on polycrystalline samples of AnF[sub 4] (An=Th, U, and Np) to examine the structures. All are isostructural with monoclinic space group [ital C]2/[ital c]. The structure of UF[sub 4] has been examined in some detail as a function of temperature. The volume of the unit cell has a minimum not at lowest temperature (15 K) examined, but rather at [similar to]350 K. ThF[sub 4] also has a larger volume at low rather than room temperature; suggesting that this effect is caused by structural rather than electronic (as ThF[sub 4] has no 5[ital f] electrons) interactions. An examination of the coordination around the two independent An sites in UF[sub 4] shows that the fluorine configuration changes appreciably around An2 as a function of temperature. At low temperatures the distorted cubic antiprism structure is considerably more puckered'' than at higher temperatures. This puckering requires more volume for the molecule, thus causing the volume to [ital expand] as the temperature is lowered. The temperature factors and the interatomic distances vary smoothly with temperature and show no unusual behavior.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6893174
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 101:11; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
ACTINIDE COMPOUNDS
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
DIFFRACTION
DISTANCE
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
INTERATOMIC DISTANCES
LATTICE PARAMETERS
MONOCLINIC LATTICES
NEPTUNIUM COMPOUNDS
NEPTUNIUM FLUORIDES
NEUTRON DIFFRACTION
POLYCRYSTALS
SCATTERING
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
THORIUM COMPOUNDS
THORIUM FLUORIDES
TRANSURANIUM COMPOUNDS
URANIUM COMPOUNDS
URANIUM FLUORIDES
VOLUME