La[sub 5]Mo[sub 4]O[sub 16]: A new structural type related to perovskite with extremely short Mo-Mo bonds
- Laboratoire CRISMAT, Caen (France)
- Rider College, Lawrenceville, NJ (United States)
The structure of La[sub 5]Mo[sub 4]O[sub 16] has been determined using single crystal X-ray diffraction methods. Samples, prepared by fused salt electrolysis, were found to crystallize with monoclinic symmetry, space group C2/m, a = 7.9638(7), b = 7.9958(5), c = 10.3345(7) [angstrom], [beta] = 95.067(6)[degrees]. Atomic parameters were refined to R = 0.031 and R[sub w] = 0.034. The structure is closely related to that of perovskite, with ReO[sub 3]-like layers parallel to (001) containing two types of MoO[sub 6] octahedra. These layers are connected to each other through Mo[sub 2]O[sub 10] units, formed by two edge-sharing MoO[sub 6] octahedra. In these units, an exceptionally short Mo-Mo distance (2.406 [angstrom]) is observed. The separation of perovskite-like layers by Mo[sub 2]O[sub 10] units may impart quasi-low-dimensional electronic properties to this mixed valence phase. The valence of the three independent molybdenum atoms is discussed. Lanthanum atoms are located in two different cages: La(1) is at the center of an incomplete perovskite cage with 12 oxygen atoms as nearest neighbors, while La(2) is in a cage bounded by four Mo[sub 2]O[sub 10] units with a distorted cubic coordination. Two of the oxygen atoms were found to be crystallographically disordered, yielding a local triclinic symmetry which through averaging becomes monoclinic. 9 refs., 3 figs., 3 tabs.
- OSTI ID:
- 5726896
- Journal Information:
- Journal of Solid State Chemistry; (United States), Journal Name: Journal of Solid State Chemistry; (United States) Vol. 105:1; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DIFFRACTION
ELECTROLYSIS
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
LATTICE PARAMETERS
LYSIS
MOLYBDENUM COMPOUNDS
MOLYBDENUM OXIDES
MONOCLINIC LATTICES
OXIDES
OXYGEN COMPOUNDS
RARE EARTH COMPOUNDS
REFRACTORY METAL COMPOUNDS
SCATTERING
TRANSITION ELEMENT COMPOUNDS
TRICLINIC LATTICES
X-RAY DIFFRACTION