We studied the effect of annealing temperature on the physical properties of WO3thin films using different experimental techniques. WO3has been prepared by hot-filament metal oxide deposition (HFMOD). The films, chemical stoichiometry was determined by X-ray photoelectron spectroscopy (XPS). The monoclinic single-phase nature of the as-deposited films, structure was changed to triclinic structure by annealing them at higher temperatures than 400°C, which has been determined by the X-ray diffraction analysis. By Raman scattering is confirmed the change of crystalline phase, of monoclinic to triclinic, since that lattice vibrational modes of as-deposited WO3and annealed at 500°C present clearly differences. WO3band gap energy can be varied from 2.92 to 3.15 eV by annealing WO3from 0 to 500°C as was obtained by transmittance measurements. The photoluminescence response of the as-deposited film presents three radiative transitions observed at 2.85, 2.41, and 2.04 eV that could be associated with oxygen vacancies; the first one is shifted to higher energies as the annealing temperature is increased due to the change of crystalline phase of the WO3.

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Abstract:© Versita Sp. z o.o. The purpose of this study was to evaluate the decay of squalene and the formation of trans fatty acids (TFAs) in the amaranth oil extracted with hexane with and without heat. Oils were analyzed by determining their chemical values, and the fatty acids were identified and quantified by using Fourier-transform infrared (FTIR) spectroscopy, in the mid-region of 400-4000 cm -1 , and gas chromatography. The FTIR analysis shows that two oil extracts (with and without heat) present a well-defined peak at 968 cm -1 , which represents the trans double bonds. The quantified TFAs are <0.5 g per 100 g of oil, which is considered as TFAs-free. The squalene content in the oil extracted without and with heat are 6.98±1.1% and 7.12±1.3%, respectively. Our data suggest that the TFAs formation is directly promoted by thermal processing and that squalene content is not affected by the application of heat during the oil extraction process in amaranth.