Structure of the intermediate Zr/sub 2/Br/sub 2/H by neutron diffraction and its structural and bonding relationships to other phases
The structures of the isomorphous Zr/sub 2/Br/sub 2/D and Zr/sub 2/Br/sub 2/H have been solved and refined by using Rietveld techniques on pulsed neutron diffraction data obtained from the powdered samples at 14 K (C2/m, a = 19.437 (3) A, b = 3.5253 (4) A, c = 5.9036 (6) A, ..beta.. = 100.98 (1)/sup 0/, R(profile)/R(expected) = 2.44 for the deuteride). The structure consists of layers sequenced Br-Zr-H-H-Zr-Br and arranged such that hydride lies in zigzag chains of distorted metal tetrahedra (or butterflies) (d(Zr-D) = 2.03-2.20 A; d(D-D) = 2.93 A). The structure is intermediate between ZrBr (ccp) and ZrBrH (hcp heavy atoms, double H in trigonal-antiprismatic interstices) and can be generated by concerted intraslab slippage from either. The hemihydride effectively retains most of the strong Zr-Zr bonding of the ZrBr parent while tetrahedral bonding of hydrogen to metal is gained that is absent in ZrBrH. The energetics associated with the contrasting structures of YClH/sub x/ (ZrBr type) and ZrBrH are considered in terms of the results of extended-Hueckel band calculations. 25 references, 7 figures, 3 tables.
- Research Organization:
- Iowa State Univ., Ames
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 6856027
- Journal Information:
- Inorg. Chem.; (United States), Vol. 25:26
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
DEUTERIUM
ISOTOPE EFFECTS
ZIRCONIUM BROMIDES
CRYSTAL STRUCTURE
MOLECULAR STRUCTURE
ZIRCONIUM HYDRIDES
EXPERIMENTAL DATA
NEUTRON DIFFRACTION
BROMIDES
BROMINE COMPOUNDS
COHERENT SCATTERING
DATA
DIFFRACTION
HALIDES
HALOGEN COMPOUNDS
HYDRIDES
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
INFORMATION
ISOTOPES
LIGHT NUCLEI
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
SCATTERING
STABLE ISOTOPES
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
400201* - Chemical & Physicochemical Properties
400202 - Isotope Effects
Isotope Exchange
& Isotope Separation