Low-alkali metal content in {beta}-vanadium mixed bronzes: The crystal structures of {beta}-K {sub x} (V,Mo){sub 6}O{sub 15} (x=0.23 and 0.32) by single-crystal X-ray diffraction

Journal Article · Thu Feb 15 04:00:00 EST 2007 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2006.11.020· OSTI ID:21015686

Zema, Michele ^[1]; Ghigna, Paolo ^[2]; Tarantino, Serena C ^[1]

---

1. Dipartimento di Scienze della Terra, Universita di Pavia, via Ferrata 1, 27100 Pavia (Italy)
2. Dipartimento di Chimica Fisica 'M. Rolla', Universita di Pavia, v.le Taramelli 16, 27100 Pavia (Italy)

The vanadium-molybdenum mixed oxide bronzes of composition K{sub 0.23}(V{sub 5.35}Mo{sub 0.65})O{sub 15} and K{sub 0.32}(V{sub 5.48}Mo{sub 0.52})O{sub 15} have a monoclinic structure with s.g. C2/m, Z=2, and unit-cell dimensions a=15.436(2), b=3.6527(5), c=10.150(1) A, {beta}=108.604(3){sup o} and a=15.452(2), b=3.6502(5), c=10.142(1) A, {beta}=109.168(3){sup o}, respectively, as determined by single-crystal X-ray diffraction. These compounds show the {beta}-Na {sub x} V{sub 6}O{sub 15} tunnel structure, which is isostructural with bannermanite, natural sodium-potassium vanadate. Structure refinements from diffracted intensities collected in the 2-38{sup o}{theta} range converged to final R=5.58% and 7.48% for the two crystals, respectively. The V atoms are distributed on three different crystallographic sites. Partial substitution of V with Mo occurs in only one of these positions. Oxygen atoms involved in vanadyl groups point toward the tunnels. The K ions in the tunnels are coordinated by seven oxygen atoms. The alkali metal content in these crystals is much lower than the solubility limit found for the analogous Na containing compound. - Graphical abstract: Perspective view of the crystal structure of K {sub x} V{sub 6-} {sub y} Mo {sub y} O{sub 15} along [010]. This vanadium-molybdenum mixed bronze assumes the {beta}-Na {sub x} V{sub 6}O{sub 15} (bannermanite-type) structure, in which Mo(VI) substitutes for V only in the V2 position. The alkali metal content in the studied crystals is much lower than the solubility limit found for the analogous Na containing compounds.

• OSTI ID: 21015686
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 2 Vol. 180; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
BRONZE
CRYSTALLOGRAPHY
MOLYBDATES
MONOCLINIC LATTICES
MONOCRYSTALS
POTASSIUM IONS
POTASSIUM VANADATES
SODIUM COMPOUNDS
SOLUBILITY
VANADATES
X-RAY DIFFRACTION