VM9O25(M = Nb, Ta), a Combination of Tetrahedral VO4 and Octahedral MO6 Units
✍ Scribed by M.T. Casais; E. Gutiérrez-Puebla; M.A. Monge; I. Rasines; C. Ruı́z-Valero
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 208 KB
- Volume
- 102
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
Crystals of (\mathrm{V}{9} \mathrm{O}{25}(M=\mathrm{Nb}, \mathrm{Ta})) have been grown by a self-flux method. The crystal structures have been determined from X-ray single crystal diffraction data. Both compounds are isostructural and crystallize in the tetragonal (\mathrm{PNb}{9} \mathrm{O}{25}) structure type, (\bar{I}), with unit-cell parameters (a=15.690) (2) (\AA), (c) (=3.8172(9) \AA), Vol. (=939.7(3) \AA^{3}), for (M=\mathrm{Nb}); and (a=15.665(6), c=3.821(3), \mathrm{Vol} .=937.6(9)) for (M=\mathrm{Ta} ;) and (Z=2). The crystal structure of tridimensional (\mathrm{V}{9} \mathrm{O}{25}) is formed by a singular combination of two (\mathrm{VO}{4}) tetrahedra and eighteen (\mathrm{MO}{6}) octahedra per unit-cell. The presence of oxygen nonstoichiometry in (\mathrm{VNb}{9} \mathrm{O}{25}) is studied. 1993 Academic Press, Inc.