| Autor: |
Liu, Y.-J., Schindler, J. L., DeGroot, D. C., Kannewurf, C. R., Hirpo, W., Kanatzidis, M. G. |
| Zdroj: |
Chemistry of Materials; February 1996, Vol. 8 Issue: 2 p525-534, 10p |
| Abstrakt: |
The intercalation of poly(ethylene oxide) (PEO) in layered V2O5 xerogel and the structural and physicochemical characterization of the products is reported. The synthesis of PEO/V2O5 nanocomposites is achieved by simply mixing aqueous solutions of PEO with aqueous V2O5 gels followed by slow water evaporation. Several different phases of PEO/V2O5 composites can be obtained by varying the component ratios. The interlayer distance of (PEO)xV2O5·nH2O varies from 13.2 Å, at x = 0.5, to 16.8 Å at x = 1.0, to 17.6 Å at 1 < x < 3, and to 18.3 Å at x ≥ 3. One-dimensional electron density calculations based on X-ray diffraction data (perpendicular to layers) show that the composites contain a monolayer of PEO molecules when x < 1 and a bilayer when x ≥ 1. The data suggest that the PEO chains are arranged side-by-side in a fully extended conformation between the layers forming corrugated mono- or bilayers. The (PEO)xV2O5·nH2O intercalation compounds are water swellable and light-sensitive. UV irradiation causes dramatic changes in the electronic structure of V2O5 and results in enhanced electrical conductivity and decreased solubility. The conductivity of the irradiated products decreases as the PEO content increases. The optical absorption spectra, electrical conductivity, thermoelectric power, magnetic susceptibility, and electron paramagnetic resonance spectra of the irradiated products are self-consistent and suggest an increased V4+ concentration in the layers and n-type charge transport. Lithium ion redox intercalation was performed on the PEO/V2O5 composites by reaction with LiI. Variable-temperature 7Li solid-state NMR studies of the Li/PEO/V2O5 materials are reported. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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