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TitleNovel materials based on organic-tungsten oxide hybrid systems
Publication TypeConference Paper
Year of Publication2003
AuthorsIngham, B., Chong S.V., and Tallon J.L.
Conference NameMaterials Research Society Symposium - Proceedings
Date Published2003
KeywordsAbsorption spectroscopy, Alkyl chain length, Electronic structure, Energy gap, Optical band gap, Powders, Thin films, Tungsten compounds, Tungsten oxide, X ray diffraction analysis
AbstractThe physical and electronic properties of tungsten oxide and some related hybrid materials have been examined via various spectroscopic techniques and the results complemented by ab initio computation. Hybrid materials based on intercalated straight-chain α, ω-diaminoalkanes in between sheets of corner-shared tungsten-oxide octahedra exhibit from XRD a linear expansion in the interlayer spacing with increasing number of carbon atoms in the amines. UV-visible diffuse reflectance spectra of several hybrid powders indicate a dominant absorption edge centred at 4.0 eV, with no apparent trend among the different samples as the alkyl chain length changes. This is higher than that of tungsten trioxide powder, which has an absorption edge centred at 2.8 eV. Ab initio calculations show that these experimental values may relate to the indirect band-gap energies of the respective compounds rather than the optical band gap. This was confirmed from the absorption coefficient results of WO3 thin films which yield a strong edge at 4.0 eV. Similar measurements of hybrid films with 1,12-diaminododecane as the organic spacer showed absorption throughout the visible range, with weak features at 4.2 and 4.9 eV.

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