Structure and properties of Y/sub 5/Mo/sub 2/O/sub 12/ and Gd/sub 5/Mo/sub 2/O/sub 12/: mixed valence oxides with structurally equivalent molybdenum atoms
Crystals of Ln/sub 5/Mo/sub 2/O/sub 12/ (Ln = Y, Gd) were grown by electrochemical reduction of alkali-molybdate/rare-earth oxide melts at 1075-1100/sup 0/C. A single crystal of Y/sub 5/Mo/sub 2/O/sub 12/, used for structure determination, was found to be monoclinic with a = 12.2376(7) A, b = 5.7177(8) A, c = 7.4835(5) A, ..beta.. = 108.034(5)/sup 0/, and Z = 2. Although the structure was refined in space group C2/m, the true space group appears to be P2/sub 1//m. In Y/sub 5/Mo/sub 2/O/sub 12/, rutile-like sheets of edge-shared MoO/sub 6/ chains linked by YO/sub 6/ octahedra are interconnected with YO/sub 7/ monocapped trigonal prisms. The Mo atoms in the chains have alternating distances of 2.496 and 3.221 A and in that respect are similar to MoO/sub 2/. However, in contrast to metallic MoO/sub 2/ both the Y and Gd compounds are n-type semiconductors with room temperature resistivities of the order of 10/sup 3/ ohm-cm. Magnetic susceptibility measurements confirm the presence of one unpaired electron per Mo/sub 2/ unit. The semiconducting behavior can be explained in terms of an unfavorable bridging oxygen coordination which prevents electron delocalization through metal-oxygen pi bonding as in MoO/sub 2/. 29 references, 5 figures, 4 tables.
- Research Organization:
- E.I. du Pont de Nemours and Co., Wilmington, DE
- OSTI ID:
- 5985943
- Journal Information:
- J. Solid State Chem.; (United States), Vol. 60:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GADOLINIUM COMPLEXES
CRYSTAL GROWTH
CRYSTALLOGRAPHY
MOLYBDENUM OXIDES
YTTRIUM COMPLEXES
BOND ANGLE
BOND LENGTHS
ELECTRIC CONDUCTIVITY
EXPERIMENTAL DATA
LATTICE PARAMETERS
MAGNETIC SUSCEPTIBILITY
MONOCLINIC LATTICES
MONOCRYSTALS
SPACE GROUPS
VERY HIGH TEMPERATURE
X-RAY DIFFRACTION
CHALCOGENIDES
COHERENT SCATTERING
COMPLEXES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
DATA
DIFFRACTION
DIMENSIONS
ELECTRICAL PROPERTIES
INFORMATION
LENGTH
MAGNETIC PROPERTIES
MOLYBDENUM COMPOUNDS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPLEXES
REFRACTORY METAL COMPOUNDS
SCATTERING
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENT COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies
360204 - Ceramics
Cermets
& Refractories- Physical Properties