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NaV 1 - x P 2 S 6 ( x = 0.16): A New Compound with Infinite Straight ( 1 / ∞ )[V 0.837 P 2 S 6 ] - Chains that Exfoliate Forming Gels

2003; American Chemical Society; Volume: 15; Issue: 12 Linguagem: Inglês

10.1021/cm0217553

1520-5002

Servane Coste, Éric Gautier, M. Evain, Martine Bujoli‐Doeuff, R. Brec, Stéphane Jobic, Mercouri G. Kanatzidis,

Advanced Condensed Matter Physics

The new 1D chalcogenophosphate material NaV0.837(6)P2S6 has been synthesized and its structure determined by X-ray powder diffraction analysis. This compound crystallizes in the monoclinic space group P21/n with a = 6.9677(3) Å, b = 5.9059(2) Å, c = 21.4537(8) Å, and β = 92.962(2)° [Z = 4, V = 881.66(8) Å3]. The Rietveld refinement led to Rp/Rwp = 0.0208/0.0271 (for 94 parameters refined). The material is isostructural with 1D-NaCrP2S6 and contains infinite (1/∞)[V0.837(6)P2S6]- chains consisting of randomly occupied edge-sharing [VS6] octahedra defining zigzag (1/∞)[VS4] ribbons that are capped by tetradendate [P2S6] ethane-like groups linked to three successive [VS6] polyhedra. Because of the nonstoichiometry of the phase, the charge balance can be written as Na+(V4+)0.486(V3+)0.351(P4+)2(S2-)6. NaV0.837(6)P2S6 is soluble in strongly polar organic solvents such as N-methylformamide (NMF). The exfoliation of NaV0.837(6)P2S6 in NMF leads to gels or to colored colloidal solutions with complex fluid behavior that depends strongly on concentration.